Hi Scott,
here is my xml,system buttons in the subgrid cancel/save as cancelled,delete functionality is lost with this customization.This customization was done with ribbon workbench with command id "command2.command"
<?xml version="1.0" encoding="utf-16"?>
<RibbonDiffXml xmlns:xsi="www.w3.org/.../XMLSchema-instance" xmlns:xsd="www.w3.org/.../XMLSchema">
<CustomActions>
<CustomAction Id="new.CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.CustomAction" Location="Mscrm.HomepageGrid.activitypointer.MainTab.Actions.Controls._children" Sequence="81">
<CommandUIDefinition>
<Button Command="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.Command" Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve" Image32by32="/_imgs/ribbon/SubmitArticle_32.png" Image16by16="/_imgs/ribbon/SubmitArticle_16.png" LabelText="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.LabelText" Sequence="81" TemplateAlias="o1" ToolTipTitle="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.ToolTipTitle" ToolTipDescription="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.ToolTipDescription" />
</CommandUIDefinition>
</CustomAction>
<CustomAction Id="new.CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.CustomAction" Location="Mscrm.HomepageGrid.activitypointer.MainTab.Actions.Controls._children" Sequence="91">
<CommandUIDefinition>
<Button Command="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.Command" Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject" Image32by32="/_imgs/ribbon/RejectArticle_32.png" Image16by16="/_imgs/ribbon/RejectArticle_16.png" LabelText="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.LabelText" Sequence="91" TemplateAlias="isv" ToolTipTitle="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.ToolTipTitle" ToolTipDescription="$LocLabels:CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.ToolTipDescription" />
</CommandUIDefinition>
</CustomAction>
<CustomAction Id="new.Mscrm.SubGrid.activitypointer.Delete.CustomAction" Location="Mscrm.SubGrid.activitypointer.MainTab.Management.Controls._children" Sequence="80">
<CommandUIDefinition>
<Button Alt="$Resources:Ribbon.HomepageGrid.MainTab.Management.Delete" Command="new.activitypointer.Command3.Command" Id="Mscrm.SubGrid.activitypointer.Delete" Image32by32="/_imgs/Workplace/remove_32.png" Image16by16="/_imgs/ribbon/delete16.png" LabelText="$Resources(EntityDisplayName):Ribbon.SubGrid.MainTab.Management.Delete" Sequence="80" TemplateAlias="o2" ToolTipTitle="$Resources(EntityDisplayName):Mscrm_SubGrid_EntityLogicalName_MainTab_Management_Delete_ToolTipTitle" ToolTipDescription="$Resources(EntityPluralDisplayName):Ribbon.Tooltip.Delete" />
</CommandUIDefinition>
</CustomAction>
<CustomAction Id="new.Mscrm.SubGrid.activitypointer.MainTab.Actions.SaveAsCancelled.CustomAction" Location="Mscrm.SubGrid.activitypointer.MainTab.Actions.Controls._children" Sequence="60">
<CommandUIDefinition>
<Button Alt="$Resources:Ribbon.HomepageGrid.MainTab.Actions.SaveAsCancelled" Command="new.activitypointer.Command2.Command" Id="Mscrm.SubGrid.activitypointer.MainTab.Actions.SaveAsCancelled" Image32by32="/_imgs/ribbon/activitysaveascancelled_32.png" Image16by16="/_imgs/ribbon/activitysaveascancelled_16.png" LabelText="$Resources:Ribbon.HomepageGrid.MainTab.Actions.SaveAsCancelled" Sequence="60" TemplateAlias="o2" ToolTipTitle="$Resources:Mscrm_HomepageGrid_activitypointer_MainTab_Actions_SaveAsCancelled_ToolTipTitle" ToolTipDescription="$Resources:Mscrm_HomepageGrid_activitypointer_MainTab_Actions_SaveAsCancelled_ToolTipDescription" />
</CommandUIDefinition>
</CustomAction>
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.AddConnection.HideAction" Location="Mscrm.HomepageGrid.activitypointer.AddConnection" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.AddNoteToActivity.HideAction" Location="Mscrm.HomepageGrid.activitypointer.AddNoteToActivity" />
HideActionId="CritSitMscrm.HomepageGrid.activitypointer.Copy.HideAction" Location="Mscrm.HomepageGrid.activitypointer.Copy" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.Import.HideAction" Location="Mscrm.HomepageGrid.activitypointer.Import" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewAppointment.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewAppointment" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewCampaignResponse.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewCampaignResponse" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewCustomActivities.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewCustomActivities" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewFax.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewFax" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewLetter.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewLetter" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewPhone.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewPhone" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.NewServiceActivity.HideAction" Location="Mscrm.HomepageGrid.activitypointer.NewServiceActivity" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.SaveAsCompleted.HideAction" Location="Mscrm.HomepageGrid.activitypointer.SaveAsCompleted" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.Send.HideAction" Location="Mscrm.HomepageGrid.activitypointer.Send" />
<HideCustomAction HideActionId="CritSitMscrm.HomepageGrid.activitypointer.SetRegarding.HideAction" Location="Mscrm.HomepageGrid.activitypointer.SetRegarding" />
<HideCustomAction HideActionId="new.Mscrm.Form.activitypointer.SaveAsComplete.Hide" Location="Mscrm.Form.activitypointer.SaveAsComplete" />
<HideCustomAction HideActionId="new.Mscrm.SubGrid.activitypointer.MainTab.Actions.SaveAsCompleted.Hide" Location="Mscrm.SubGrid.activitypointer.MainTab.Actions.SaveAsCompleted" />
<HideCustomAction HideActionId="new.Mscrm.SubGrid.activitypointer.MainTab.Actions.SetRegarding.Hide" Location="Mscrm.SubGrid.activitypointer.MainTab.Actions.SetRegarding" />
</CustomActions>
<Templates>
<RibbonTemplates Id="Mscrm.Templates" />
</Templates>
<CommandDefinitions>
<CommandDefinition Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.Command">
<EnableRules />
<DisplayRules />
<Actions>
<JavaScriptFunction FunctionName="BulkTaskApprove" Library="$webresource:new_Labor_Task_Approval_Main">
<CrmParameter Value="SelectedControlSelectedItemIds" />
<CrmParameter Value="SelectedControlSelectedItemCount" />
</JavaScriptFunction>
</Actions>
</CommandDefinition>
<CommandDefinition Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.Command">
<EnableRules />
<DisplayRules />
<Actions>
<JavaScriptFunction FunctionName="BulkTaskReject" Library="$webresource:new_Labor_Task_Approval_Main">
<CrmParameter Value="SelectedControlSelectedItemIds" />
<CrmParameter Value="SelectedControlSelectedItemCount" />
</JavaScriptFunction>
</Actions>
</CommandDefinition>
<CommandDefinition Id="new.activitypointer.Command2.Command">
<EnableRules>
<EnableRule Id="new.activitypointer.EnableRule1.EnableRule" />
<EnableRule Id="new.activitypointer.EnableRule0.EnableRule" />
</EnableRules>
<DisplayRules />
<Actions />
</CommandDefinition>
<CommandDefinition Id="new.activitypointer.Command3.Command">
<EnableRules>
<EnableRule Id="new.activitypointer.EnableRule1.EnableRule" />
<EnableRule Id="new.activitypointer.EnableRule2.EnableRule" />
</EnableRules>
<DisplayRules />
<Actions />
</CommandDefinition>
</CommandDefinitions>
<RuleDefinitions>
<TabDisplayRules />
<DisplayRules />
<EnableRules>
<EnableRule Id="new.activitypointer.EnableRule0.EnableRule">
<CustomRule FunctionName="ulsdata" Library="$webresource:new_cancel_disable_task">
<CrmParameter Value="FirstSelectedItemId" />
</CustomRule>
</EnableRule>
<EnableRule Id="new.activitypointer.EnableRule1.EnableRule">
<CustomRule FunctionName="isNaN" Library="$webresource:new_jquery_1.6.2.min.js" />
</EnableRule>
<EnableRule Id="new.activitypointer.EnableRule2.EnableRule">
<CustomRule FunctionName="user" Library="$webresource:new_disablerecord_onowner_selection">
<CrmParameter Value="FirstSelectedItemId" />
</CustomRule>
</EnableRule>
</EnableRules>
</RuleDefinitions>
<LocLabels>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.LabelText">
<Titles>
<Title description="Approve" languagecode="1033" />
</Titles>
</LocLabel>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.ToolTipTitle">
<Titles>
<Title description="Approve" languagecode="1033" />
</Titles>
</LocLabel>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Approve.ToolTipDescription">
<Titles>
<Title description="Approve Description" languagecode="1033" />
</Titles>
</LocLabel>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.LabelText">
<Titles>
<Title description="Reject" languagecode="1033" />
</Titles>
</LocLabel>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.ToolTipTitle">
<Titles>
<Title description="Reject" languagecode="1033" />
</Titles>
</LocLabel>
<LocLabel Id="CritSit.HomepageGrid.activitypointer.MainTab.Actions.Reject.ToolTipDescription">
<Titles>
<Title description="Reject Description" languagecode="1033" />
</Titles>
</LocLabel>
</LocLabels>
</RibbonDiffXml>