Fold up and Fall in

Fold up verb - Bend or lay so that one part covers the other.

Fall in and fold up are semantically related in collapse inward topic. In some cases you can use "Fall in" instead a verb "Fold up".

Fall in verb - Break down, literally or metaphorically.

Fold up and fall in are semantically related in collapse inward topic. Sometimes you can use "Fold up" instead a verb "Fall in".