what was that show? help me remember

what was that show? help me remember
i have vague memories of a show i used to watch back in early 90s probably before or shortly after spellbinder aired. there is not much i can recall but ....the lead characters were brother and sisters maybe . they used a boat like machine which was a time machine or to move between parallel universes. there is one episode which i distinctly remember...they end up in an universe/time where people have found a way to be immortal but they stopped reproducing to preserve resources. they have robot babies which look like human child. a wealthy family tries to keep them imprisoned as they want real babies. at one point the girl lead charecter uses acid to melt lock and escape. robot baby probably also helped them escape. not much....but i remember i used to like it a lot as a kid.