"My stepdaughter is my husband's daughter."

Translation: Ma belle-fille est la fille de mon mari.

[rolotow]

I constructed the sentence ...
'Ma belle-fille est la fille de mon mari' which was accepted ... however
I believe that 'belle-fille' is the translation for 'daughter in law' ... and
'Demi-fille' (the correct translation for stepdaughter) is not available for selection into the sentence

[Sitesurf]

"Demi-fille" is not a French word. This is why it was not available for selection.

Please use a dictionary if you are not sure about a word.

"Ma belle-fille" is the same for "my daugher-in-law" or "my stepdaughter".

"Demi-" is used only as "demi-frère" (half-brother) and "demi-soeur" (half-sister).

[rolotow]

I apologise! Have since checked via Google translate .. .however ... how do i tell if 'Ma belle fille' is my stepdaughter or my daughter in law

[Sitesurf]

You can still add info or use "la femme de mon fils" or "la fille de ma femme".

[EPOSantos]

As in the example. Context always helps.