@MummyTo4BoysXXXX , thanks for PMing me and for sharing the names. The first name is unusual so I'll try to use something of a fairly similar nature. One of the middle names is outside the top 150 names.
The name that would be hyphenated with the first name is Rose.
The full name will be something like Dahlia Rose Lucy Maisie Smith.
Dahlia and Rose are both flowers but not related. Hyphenating them seems a bit silly, makes no sense and seems confusing.
Most of the hyphenated names in current use seem to be Something-Rose or Something-May. I find Rose/May/Grace as a middle name a bit meaningless and just a middle name for the sake of it, so I'd remove it.
I think that two middle names is a bit too much, and the two -ie/-y names a bit clunky but middle names aren't used much, so they could be ok. The 'Maisie' is OP's own name, so I'd remove it. The little girl will always be 'Maisie''s daughter. The 'Lucy' is a family name.
I'd go with Dahlia Lucy Smith. It looks better than
Dahlia Rose Lucy Maisie Smith.
(OP's name is classier than Maisie)
Dahlia-Rose Smith will appear as Smith, Dahlia-Rose on lists, work badges etc. If the surname is long, the first name will be truncated
e.g Smithson - Dahlia-Ro