Could she be a daughter of John of Grenane and Bahee Skillicorn? The folorn claim to land would be typical of that branch.

I did have a Catherine down as their child, married to John Lewn of Ballameanagh, Onchan, but decided she was the daughter of Donald of Raby instead.

You now have to account for a sister Elizabeth, as well.

Have you found Bahee's will?