Thanks Ravi for quick turnback and apologize for incomplete details.
We have 1:N out of box relationship between contact & opportunity entity right. On opportunity form, we have account & contact lookup fields. Say user filled in account lookup field on opportunity and saved it. Now user clicks contact lookup field and he doesn't find it so clicks on "New Record" button on the contact lookup which opens up contact quick create form. Ideally, the account lookup field on opportunity should map to account field on contact quick create form but it isn't working.
I tried in brand new vanilla instance, but it is mapping fields as per relationship mapping when you create an opportunity from contact. But when creating contact from opportunity its not mapping it.
FYI, i also tried using unsupported DOM elements like window.parent/window.top.parent.frames[0], but unfortunately i am not getting any of the parent attributes on UCI. Not sure how to achieve this though?