Thanks for a good stab, Ronald.Perhaps they all do connect back in County Mayo or Scotland, lost in the mists of the 17th C.
But your only Michael McAndrew (b.abt.1859-d.abt.1876) remained in Crossmolina and did not married.It is possible but unlikely that this teenager sired offspring.Also, he is too late to be connected directly to my Michael (b.abt.1830-d.abt.1903) who was apparently in Iowa by 1859 starting his own family with Honora Fuery McAndrew.
A strong clue for 19th C. family connections can be found in given names.Traditional name-the-baby pattern is not an absolute, but is a predictor.They sometimes deviated to name a kid after a rich shirt-tail relative.Search on "traditional Irish naming pattern" with entire phrase in quotes.Bartholomew/Bartley shouts out for this attention.
I hope that your careful listing here may help someone else to connect to you. MMM