Thank you to the 3 folks who have responded so far. Apparently we have done some dangerous/stupid things without realizing it. Appreciate your warnings and wise council.

Each of you mentioned ELECTRUM. Is this a program/app/utility that can be downloaded on an iPhone (to make things easier for my father)? Or can it be downloaded on a Mac (I/we only use  Mac computers, no PCs/windows machines at all ever)? Or is this a PC/Windows computer mandate type thing?

Thanks again for the responses.