Hi Terri,
welcome back to the Forum. Hope you are doing fine up there in Canada. The name "Valentin" sounds quite french to me. I don't think that it originates from Madagascar because they usually have very long names there. Another option could be India from Pondicherry as in the times back then it was a French colony in India and some people from Pondicherry emigrated to Mauritius. Well, but who knows if the Valentin family stayed in Madagascar for sometime and then moved on to Mauritius and then to Canada...
Hope you'll get closer in your search and hopefully maybe some people in Mauritius might respond...