I’ve always paired [name_f]Sadie[/name_f] and [name_f]Maisie[/name_f] together. They’re both incredibly sweet, but usable. I think they are similar, but would fine as sisters 
I agree with the suggestion to name the child [name_f]Margaret[/name_f] and then decide on the diminutive later. There are loads!
[name_f]Maisie[/name_f]
[name_f]Daisy[/name_f]
[name_f]Molly[/name_f]
[name_f]Polly[/name_f]
[name_f]Margie[/name_f]
[name_f]Greta[/name_f]
[name_f]Pearl[/name_f]
[name_f]Margot[/name_f]
[name_f]Meg[/name_f]
[name_f]Peggy[/name_f]
[name_f]Rita[/name_f]
[name_f]Maggie[/name_f]
Can’t go wrong really. Lots of these are cute
I love [name_f]Polly[/name_f]
I think they’re similar in the fact that they’re older nicknames coming back into style, but I don’t think they’re too close to use. I have two older siblings and all of our names begin with K or C (which wasn’t intentional on my mom’s part) and we frequently got called each other’s names, but it wasn’t a huge deal. If my mom can have two daughters whose names both begin with K, are 5 letters and two syllables, and end in -ie, then [name_f]Sadie[/name_f] and [name_f]Maisie[/name_f] will be fine.
I do find [name_f]Sadie[/name_f] and [name_f]Maisie[/name_f] a bit similar, since they have so many similar sounds- the S, the long A, the “ee” sound at the end- and they’re both two syllables. If [name_f]Maisie[/name_f] was always [name_f]Maisie[/name_f] [name_f]Kate[/name_f] though that would be okay, as the [name_f]Kate[/name_f] part would differentiate the two more. Also, what about just [name_f]May[/name_f]/[name_f]Mae[/name_f]? Another [name_f]Margaret[/name_f] diminutive would be good too.
Not in my opinion. They only share the same -ie ending. I would pronounce [name_f]Maisie[/name_f] as may-zee so the S letters are pronounced differently.
[name_f]Sadie[/name_f] and [name_f]Maisie[/name_f] are too similar, in my view. [name_f]Molly[/name_f] works much better. [name_f]Pearl[/name_f] or [name_f]Megan[/name_f] could honour a [name_f]Margaret[/name_f]. [name_f]Sadie[/name_f] is beautiful, btw - love that name so much.
I find them too similar, unfortunately.
However, I think [name_f]Greta[/name_f], [name_f]Megan[/name_f], or [name_f]Pearl[/name_f] would be AMAZING with [name_f]Sadie[/name_f] (love [name_f]Sadie[/name_f]!!) and great ways to honor your grandmother.