There is no automation. I've made some customizations for the same thing.
I made form "FA Phys. Inventory Journals" and function "Create FA Phys. Inventory". I get list of FA in this Journal with Quantity=1 and FA Posting Type=Disposal. If FA doesn't exist, you need to put 0 in Quantity field.
After that, you van post.
This is described briefly, but this is idea if you know development.