A successful evening's hunting -
Isaac Mann. Born Norwich 1710, entered Trinity College Dublin in 1730 under the patronage of Robert Jocelyn (later the Chancellor of Ireland). Died Bath, Somerset 10 December 1788, interred at the Episcopal Chapel of the Bishop's summer palace at Ballinapsig, Cork on 31 December 1788.
Isaac Mann did indeed adopt his brother's children after his brother died, and he took their mother into his home as well. He never married. There were 5 children -
Samuel - erected a monument to his uncle in the Epicopal Chapel at Bishopstown House at Ballinaspig "... to the memory of his beloved and much honoured uncle...Saml Mann has caused this monument to be placed here." The monument was moved to St Finbarre's Cathedral in Cork in 1845.
Frances - married Christopher Townsend
John - married Mary Smyth (Isaac Mann leased Bishopstown House to Nicholas Smyth in 1785)
Henry - married Jayne Smyth
Susanna Maria (or Marie) - married Rev. Joseph Weld in 1775 in Cork (ref. Brady p.451 "Susanna Maria Mann, niece, ward and adopted daughter of Isaac Mann, Bishop of Cork and Ross"
I have a photo of the portrait of Isaac Mann that hangs in the Bishop's Palace in Cork - they hold the copyright.
Isn't Mr Google wonderful?