my sister thinks her tiger turtles are pregnant and not sure how to handle it

any help would be great

I've never heard of this species (pic/s?) but if its freshwater turtle, she will need a land area of suitable sandy/loamy soil to bury her eggs in.
You could build a pond if you have space, but iff not, perhaps temporarly house her in an old bathtub with atleast 1 third land.
Eggs layed in the water are often unsavable after a certain time i beleive.
You could google for information, about incubation temp/time etc.

thanks will let her know

Any chance of pics Caren? Update on your freinds turtle?