If I have a visa with a “family stay” stamp that permits me to stay in the home of family or friends, can I use that same visa to stay in a casa particular at another time during that same visit?
Yes, on a “family stay” visa you are permitted to also stay in a casa particular or legal homestay during the same trip to Cuba.
However, family stay visas are NOT transferrable to other stays with other family or friends. If, during the same visit to Cuba, you have Cuban friends in two different parts of the country, or even in two different parts of the same city, you will need to apply for a second “family stay” visa when you change location. It is up to the discretion of immigration whether or not to issue any such visas.