new to this site and if this topic is elsewhere i apologize for the repeat.
recently i purchased a female lyre-tail sword and she was definitely pregnant, almost about to pop. i carefully moved her to a breeder cage and within hours she was dead, no fry born. i returned her to the store and got a replacement. she too was in the family way and ready to blow. this time i did nothing but watch her. today she is very listless and not eating. staying in one spot and when she does move she looks very awkward. she really looks about to bust and i am worried that perhaps she cannot expel her fry, possibly like the last one, or is this normal behaviour. i have had fish in the past and started over in this last year or so. water is perfect, cycled, planted, no over crowding, regular partial water changes etc. etc.
i have had platy fish give birth recently in another tank and some those fry platys survived (4 of them anyway, rest were picked off) also had fancy guppy fry, again 4 survived.
i didn't notice any problems like this lyre-tail is displaying.
what do i do? is there a way to help a fish expel fry when they are positively going to give birth? or do i just let things be? i really don't want to do this again with another replacement if this one dies.

i have:
a 5.5. gal with separated bettas,
a 2 gal with dwarf frog and betta,
a 60 gal. with orandas.
a 15 gal with hi fin platy's and lyre-tail swords
a 30 gal with assorted guppy molly platy
a 5.5 with 8 fry from platy and guppy

also mom to 5 cats, 4 ferrets, 3 lizards, 1 human.