Morning Donella - I am sorry to read of your losses.
If I have understood correctly then your Mum is still alive so any change of legal ownership would require here to transfer the whole of the legal title as appropriate. You can't for example transfer a half share as that relates to their beneficial ownerships and not the legal ownership that's always dealt with as a whole.
Before making any changes I would recommend seeking legal advice to consider what options exist and what's 'best' in such cases depending on your Mum's health/future plans as well as your own and the 'children's' ages and future plans re property etc
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