I do not think you will be able to keep them in the same tank as the adults, unless you can find a divider thathas a fine enough mesh that the little guys cannot get through it. As soon as they are big enough for the adults to see them, they will eat them.
Fry left in the pond with the adults will have a certain proportion of them live, mainly because there are so many hiding places. Because of the algae and bugs and other things available in the pond, the fry find food and some will thrive.
In a tank, there is limited food for fry - and limited hiding spots. If you do separate the fry from the adults, you need to realize that you have to feed the fry - separately and with special food - and many times a day.
Congratulations!!!!