Gift of property from estate

I am sure this is simple but could someone clarify the process, please. Its partly a conveyancing question

Mother has been left APR and non-APR land in her husband’s will. Her sons are executors. She has done a DOV passing the APR land to sons. She also wants to make a PET of the non-APR land.

I don’t think the sons as execs can assent all the property to themselves, I think it must be1) an assent of APR land only to them and 2) an assent of non-APR land to mother, who then does a TR1 to the sons for no consideration. Is that right?

Thanks

Matthew