Q:

Do Tzipporah and her children need to retell the story of Exodus if they weren't there?

At the beginning of Parashat Yitro, Yitro bring Tzipporah and her children to the camp after the tenth plague, the sea and battle with Amalek.
Does their absence these events have an effect on their commandments to retell of them?
These people are not modern people who couldn't be there. They could have been there but weren't.

A:

Even converts are required to tell over the story of yetziat mitzrayim. As a general rule, all mitzvot (commandments) apply to every individual even if the reasoning doesn't fully apply to them. 

