Hi partner,
You could use C# to insert new options to option set field.
1.Create a console app project and connect to Dynamics 365.
https://arunpotti.wordpress.com/2018/02/03/step-by-step-to-connect-dynamics-365-crm-online-v9-x-using-c-console-application/
https://docs.microsoft.com/en-us/powerapps/developer/common-data-service/xrm-tooling/sample-simplified-connection-quick-start
2.Add options to the option set field.
// Create a request.
InsertOptionValueRequest insertOptionValueRequest =
new InsertOptionValueRequest
{
AttributeLogicalName = "new_picklist", //field name
EntityLogicalName = Contact.EntityLogicalName,//entity name
Label = new Label("New Picklist Label", _languageCode)//label
};
// Execute the request and get the value.
int insertOptionValue = ((InsertOptionValueResponse)svc.Execute(
insertOptionValueRequest)).NewOptionValue;
Console.WriteLine("Created {0} with the value of {1}.",
insertOptionValueRequest.Label.LocalizedLabels[0].Label,
insertOptionValue);
https://docs.microsoft.com/en-us/dotnet/api/microsoft.xrm.sdk.messages.insertoptionvaluerequest?view=dynamics-general-ce-9
BTW, adding 100 options is a very heavy work and it is also not easy to find the option you want in the 100 options without searching feature.
I suggest that you could use Look up Field insead, you just need to create another new entity and build a 1:N relationship between the main entity and the new custom entity.
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As you can see in the picture, yo could use filter or searching feature in the lookup field which makes it easier to find a special record.
https://docs.microsoft.com/en-us/dynamics365/sales-professional/use-lookup-fields-forms
Hope it helps.
Best Regards,
Leo