Changing the Availability Check key in an existent Sales Order line

Hello gurus.

Is it possible to modify the Availability Check key (VBAP-MTVFP) of a material in an existent Sales Order line?

I changed it in the material master, but since documents are not automatically updated, I wanted to modify this value in an existing sales order line. I am not even able to find the field in it.

I had to delete the order line and create it again, but then I have troubles getting the exact same confirmed date that I had before.

Any help? Thank you.