Definitely works for [name_f]Margo[/name_f]/[name_f]Margot[/name_f]. I have an aunt named Margrita that goes by both [name_f]Maggie[/name_f] and Grita so it seems to me any Marg- name would work.
[name_f]Margot[/name_f] is not a nickname? At least I don’t think it is. I love the name [name_f]Margot[/name_f], it’s so pretty! [name_f]Maggie[/name_f] is cute but I love [name_f]Margot[/name_f] as a name by itself.