I agree with this, when designing a more detailed ERD- I usually encounter the use of minimum and maximum cardinality for the relationships. It should be able to be set manually (by default, automatically). For example: table A and table B, where table A has ONE to TWO (1,2) relation to table B, where table B has ONE to ONE relation to table A.

This is a great suggestion. We currently only support Chen notation, and the Crow's feet notation is more expressive, as you have pointed out. We'll try to make this happen in our next iteration of the ERD feature.