If a crofter obtained title to their whole croft comprising in bye land and an apportionment, would they have to apply for Commission consent to divide the croft prior to transferring the part comprising the apportionment to another party?

Yes. Sub-section 19D(1) states that An owner-occupier crofter may not transfer (whether or not for valuable consideration) any part of the owner-occupiers croft without first dividing the croft into the part which the owner-occupier crofter proposes to transfer and the part which the owner-occupier crofter proposes to retain. Sub-section 19D(6) provides that any transfer of ownership of any part of an owner-occupied croft which is not a new croft created by a division under this section, and any deed purporting to transfer ownership of that part, is null and void.