Hello @Susan4178 and welcome to ABB CC from across the lands and oceans in Auckland, New Zealand
What a beautiful inviting Heritage treasure you have.
It's interesting for a New Zealander to read you have to have a Pool alarm.
I've never heard of that before.
Have you looked using related keywords in the Search box here in CC?
Someone else may have asked a similar question in the past, and there are many other topics on swimming pools which you may find helpful.
To cover your basis, it's a wise idea to have an agreement signed for both parties peace of mind.
As an aside, we have regulations around swimming pools having to be fenced off.
Those bylaws were introduced across New Zealand, notably in Auckland, from recall in the 1990''s after we had our perfectly functioning local borough Councils gobbled up into Auckland City Council governance.
All the best