In this type of situation, the four receivers are spread across the field, working as pairs. (See Horizontal stack offence) One goes long and one goes short and they rotate. The defenders can also do this. Once the defenece realises the offence, then the two defenders on the left can decide between themselves that one will mark the deep and one will mark the short.
As for the handlers, the people marking these must realise that their mark will change depending on where the disc is. Usually, if it is on a sideline, then the marker will force sideline and the defenders on the handlers will mark the dump very close.