Where a pupil is registered at two schools, one must be designated as their ‘main’ school, with this school only allocating them a UPN.
Lle bydd disgybl wedi'i gofrestru mewn dwy ysgol, rhaid i un gael ei nodi fel y 'brif' ysgol, a dim ond yr ysgol hon ddylai ddyrannu RhUD iddo.