Restrict Projects list on PO Distribution Screen

Dear Experts,

We have the following requirement :

1 : Default expenditure Org on the PO distribution Screen : This can be achieved by setting PA: Default Expenditure Organization in AP/PO profile option.

2 : Similarly we also want to restrict the list of projects and expenditure types on the PO distribution screen. How can this be achieved.

Appreciate your prompt response

Thanks,

Sirisha