+1 on Mt Spokane Photography
... so in other words, every lens that will work on 650D will also work on 7D, but only EF will work on the 5D as well
... and every lens that will work on 5D (so EF yes, EF-S no), you will also be able to use on the 650D
however (you might be already familiar with this), compared to the full frame 5D, the 650D and 7D have a 1,6 crop factor, so if you put a 100mm lens on a 650D/7D, it will give you effective focal length as a 160mm on a 5D or, a 16-35mm on a 5D will be like a 10-22mm on a 650D/7D...
so adding 5D to the 650D might actually give you more options, but restricts you on the EF lenses for the 5D
plus, there are third party lenses (Tokina, Sigma, Tamron, Samyang...) that also make some lenses only for DSLRs with an APS-C sensor (like 650D/7D) and some for full frame DSLRs (5D) and have some labeling for it (like Canon has the EF/EF-S) and state in the specifications whether it is for full frame as well, so you might want to look at that as well