For such calculations, the member should be treated as a full member of the council and therefore any substitution should be open only to a member of the same political group.
Ar gyfer cyfrifiadau o'r fath, dylid trin yr aelod fel aelod llawn o'r cyngor ac felly dylai unrhyw drefniadau dirprwyo fod yn agored i aelodau o'r un grŵp gwleidyddol yn unig.