Byddai gan gynghorau'r opsiwn o uno o hyd dan y cynlluniau newydd, a lle bo cytundeb lleol i wneud hyn bydd Llywodraeth Cymru'n helpu i'w wireddu.
Councils would still have the option of merging under the new plans and, where there is local agreement for this, the Welsh Government would work with them to make it a reality.