This might seem like a weird request, but... I'd like a splitter/merger separate from the normal ground splitter/merger that can attach to an existing structure and come out at the same level as the structure, even if not touching the ground. It would be really useful for things like the Assembler, Manufacturer, etc. with multiple inputs.
This would work by having it come out of whatever attachment like a pole, unmoving, only extending and retracting. You could put in a system where you can't extend the floating splitter/merger/conveyor belt past the last "anchor point" (pole/attachment to ground structure) if you don't want people to "cheese" floating conveyor belts across the whole map (though technically you can do that right now by just removing the conveyor pole after placing the conveyor belt anyways)