Here’s a list of a few that might work! In my opinion, the best way to connect all three names would be making the third name slightly longer than [name_f]Jane[/name_f] and shorter than [name_f]Marigold[/name_f]. I think this would create a nice balance and would help avoid having one name stand out too much.
[name_f][/name_f]Additionally, I think that having a name that ends in A might help your third daughters name stand out a little more and prevent it from matching too much with either [name_f]Marigold[/name_f] or [name_f]Jane[/name_f]. I also included a few names that are four letter M names because those would visually create a balance between the M in [name_f]Marigold[/name_f] and the length of [name_f]Jane[/name_f].
[name_f][/name_f][name_f]Dorothy[/name_f]
[name_f][/name_f][name_f]Lillian[/name_f]
[name_f][/name_f][name_f]Willow[/name_f]
[name_f][/name_f][name_f]Katherine[/name_f]
[name_f][/name_f][name_f]Helena[/name_f]
[name_f][/name_f][name_f]Caroline[/name_f]
[name_f][/name_f][name_f]Delia[/name_f]
[name_f][/name_f][name_f]Macy[/name_f]
[name_f][/name_f][name_f]Myra[/name_f]
[name_f][/name_f][name_f]Adela[/name_f]
[name_f][/name_f][name_f]Cecilia[/name_f]
[name_f][/name_f][name_f]Cecily[/name_f]