Hello,
We have a requirement where we need to open 'Quick Create' form for opportunity products on click of opportunity product grid plus '+' button on 'Opportunity Form', We've enabled the 'Quick Create' functionality for the 'Opportunity Products' and created a quick create form, Created a new view and added on 'Opportunity' form still it's not opening quick create form instead opening main form, we also tried by hiding add existing button for opportunity products views using ribbon workbench.