Complex sentence: During this marriage she made generous donations to Roman Catholic charities and to Georgetown University, Washington DC, who asked for her portrait, which was painted in 1899 by the Swiss-born American artist Adolfo Müller-Ury (1862--1947).
Split into simpler sentences: During this marriage, she made generous donations to Roman Catholic charities and to Georgetown University. The latter asked for her portrait, which was painted in 1899 by the Swiss-born American artist Adolfo Müller-Ury (1862--1947).