My mum doesn't have her in account, so I was hoping I could link it to mine, (thinking I might be able to select which test I wanted to apply at a given moment to my own tree) but I've just find more info and it doesn't look like it is possible: Each adult taking the test needs their own account. Only one DNA kit can be registered per account, except for tests for minor children.
Mum doesn't have an Ancestry account, and wouldn't be able to manage one, so I am looking for alternatives now.
If I signed her up for a free account (with her consent) that I then managed, I am not sure how much information regarding matches she/I would get to see.
There is one side of her family that she knows nothing about, so the hope is that her DNA rather than mine might make it slightly easier to identify relatives from that side.