Hi Yasser.
If I understand well, you want running a proposal only for few selected items ok?
For that you need select open items:
Go to Tcodes: FBL3N or FBL5N, choose the documents numbers of the open items
Go to Tcode F110 "Free Selection" > "Selection Criteria" in "Field Name" select "Document Number". then put the documents numbers of open items there. So, the select items will be in the proposal.
Example
Kind Regards
Jandoval Nascimento