I love this!
[name_f][/name_f]If [name_f]Thea[/name_f] were my daughter she would be [name_f]Thea[/name_f] [name_f]Mary[/name_f] or maybe [name_f]Thea[/name_f] [name_f]Colette[/name_f].
[name_f][/name_f]For [name_f]Thea[/name_f] as a middle name I’d go with [name_f]Marigold[/name_f] [name_f]Thea[/name_f], Évangeline [name_f]Thea[/name_f] or [name_f]Emmeline[/name_f] [name_f]Thea[/name_f].
[name_f][/name_f]For siblings:
[name_f][/name_f][name_f]Thea[/name_f], [name_f]Polly[/name_f] and [name_m]Jem[/name_m]