A mystery solved!! Woohoo!:)
Turns out Joseph Holmes' (Nellie and Florence's dad) second marriage was to the cousin of his first wife. No wonder the same names going round and round was giving me a headache, lol! This means that (besides potentially having something to shake my finger at one of my ancestors for) he did actually keep his youngest child, Florence, with him, but left Nellie elsewhere..
Many thanks to everyone helped me by posting a reply! Especially Tazzie, Anna and Geoffe who's tireless efforts (including having to explain everything to me in words of one syllable) helped me to unravel it all. Thanks guys!!:)
Cat