OK so there was this boy and girl, they were twins... and they got separated or something... something maybe having to do with a vegetable or fruit cart? Anyway... they meet again some time later and when they put their palms together this purple light is there... and then they have to help do something... I don't remember much more but it was from the 80s or 90s... please help.

OK I think I found out... is it return to witch mountain?

Escape To witch Mountain.

Return to Witch Mountain is when they come back to Earth for a visit, and Tony get kidnapped.

I remember that movie, damn haven't seen that in years

Come to think of it, it wasn't that bad

Omg omg omg I know exactly what movie you're talking about! And I've never been able to find the name. I read the title Escape to Witch Mountain in a book I was reading and it rang a bell so now I have verification! I'm so excited! Now I have to go rent it.
Haha
OK well thanks for asking your question!:)