I would like to draw up a notarial will to make one of my daughters a universal legatee. My notary is asking me to appoint two witnesses. Can I choose my daughter's PACS partner?

Yes, article 975 of the French Civil Code stipulates that "neither the legatees in any capacity whatsoever, nor their relatives or allies up to and including the fourth degree (...) may be taken as witnesses to the will by public deed". The PACS partner is neither a relative nor an ally, as the PACS only creates a contractual relationship. (Cass. 1ère civ., February 28, 2018, n°17-10876).