Is one considered a brother by suckling if he suckled from the mother a satiating suck once or more, without remembering the number of sucklings?

There is no difference in the prohibitive suckling whether the suckling from the breast occurred at the same time or at different times. Thus, whoever suckles from a woman becomes a brother to all her children. A condition for suckling to be prohibitive is that it consists of five known and satiating sucklings, based on the hadith (definition) of Aisha, may Allah be pleased with her: "Among what was revealed in the Quran were ten known sucklings that make marriage unlawful, then they were abrogated by five known sucklings." The default is non-prohibition, so prohibition is not established by doubt regarding the existence or number of sucklings.