Restrict the user to input few accounts manually

Hello Experts

We have a requirement to restrict the user to use few natural accounts manually however when they match the invoice to PO or project is populated system should let it happen

We cannot use security rule as security rule restricts the account for matched invocies as well

I believe the only way is through personalization, has any one experienced this issue?

We are in R12.1.2

Thanks

Dilip