Support One-to-Many relationships on objects

Right now you can only create object relationships as one directional single relations ships, meaning you would have to create a relationship twice to have a one-to-one bidirectional relation. or many-to-many (which is currently fine, but i would like to see also the ability to limit many-to-many to a subset of objects based on a filter and have it remain bidirectional) but currently one-to-many relationships are not supported, which would help my workflows dramatically, as i want to ensure some fields never have more than one relation in a certain direction.