What do you think the longer form of [name_m]Dacha[/name_m] is?
The Nameberry entry says it’s a Russian diminutive of [name_m]Alexander[/name_m].
I think it makes sense for a Da- name like [name_u]Daniel[/name_u] as well, but I’m not Russian so that may be considered inappropriate and I wouldn’t know.
Maybe [name_f]Natasha[/name_f]?