EWM : Advance Production Integration - Single order staging

Hello,

Is it possible to add a stock to the already existing "Single Order" at the PSA ?

For example , I have the raw material at the PSA which is single order staging and If I want to do an ADHOC movement to move more stock of same product to the PSA, would it be possible, if yes then how? I ran the same process using cross order staging and it works fine.

Any suggestions?