Allow to Create entity record only from subgrid

Hi, all.

I am using MS CRM 2016 On-Premises.
I am configuring child entity and parent entity.

I need to allow child entity creation only from subgrid on parent entity.

And to disable child entity creation from other child entity views and forms and from advanced find.

If I will use Create privileges - it won't allow me to create child entity record from subgrid?
Are there any ways to realize it?

Thank you.
With regards, Yuriy.