I have 30 citrus cultivars grafted into one rootstock and I hope it is more than enough to convince you that it can be done.

Scroll to picture number 39 on the sample grafts pics below. That was the time when there were just 27 cultivars into one tree.

Here is a link that might be useful: sample grafts

Holy-Moley! No way. I guess that answers my question.
Thanks Joe

Tropical_Beduin's check out MrTexas site as well. He is in your area & has a multi grafted citrus tree as well.

Virtually any citrus can be grafted to virtually any other. If you do that, though, be aware that any virus or viroid disease in any of the parts will immediately move to all the other parts. As long as your budwood is "clean," you're ok. But if you get a scion that is infected, and one or more other parts of your tree are susceptible, you may lose them. For example, if you are grafting anything onto grapefruit stems, and tristeza virus is introduced into the tree, everything above the grapefruit will be killed. If anything is on poncirus or its hybrids, and you introduce exocortis viroid, everything above the poncirus will be severely stunted for life. If you introduce cachexia viroid, all of your mandarin hybrids will become stunted and unhealthy.

The problem here is that other varieties of citrus are tolerant to these organisms, so may be totally healthy-looking and symptomless. So merely picking wood from an apparently healthy tree is not a guarantee that the tree is free of some pathogen that would severely affect other varieties.

Whether you'll pick up such a disease depends on where you get your scion material. In the out-of-doors in Florida, your likelihood of acquiring tristeza is nearly 100%, and exocortis, maybe 50%, particularly if collected from older trees.

Thanks Malcolm, I'll keep that in mind for next spring, I'm going to try grafting.

Most of my budwoods are certified disease free from UCR, they have a budwood program. I also get some from friends whom I know love their citruses more than their wives, I mean, who cares so much about citruses that a single spot on the leaves never gets unnoticed. Follow advice of trying to have true named cultivars and disease free and you should be okay.

Joe that is very cool!

Can someone get very specific on the citrus grafting. I successfully grafted almost every kind of stone fruit and nut you can think of but I have ZERO luck in getting any of my like 50 attempts to get citrus to graft. Any guidance would be greatly appreciated.

What season do you graft in?
What size is the bud wood?
What size is the scion?
Is the wood taking the graft, green or hardened?
Do you use parafin tape, wax or rubber bands or what exactly?
Do you have more luck with whip or bud grafting?

Some of this may apply to you.

Here is a link that might be useful: Budding notes

Joe:
". I also get some from friends whom I know love their citruses more than their wives"
Are you talking about me? My wife often times lock me out at my backyard and threatened my citrus with pouring clorox on them.

"If anything is on poncirus or its hybrids, and you introduce exocortis viroid, everything above the poncirus will be severely stunted for life."

Is this above and beyond the normal dwarfing on Poncirus or is this part of the mechanism? Is the infected rootstock/scion plant ruined for fruiting, or is the plant just very highly dwarfed?

Then there are two types of Tsn-RNA inocculum.
type IIa - Enhances fruit sizes on Trifoliate orange rootstock
type IIIb - Reduces tree size and enhances fruit size on trifoliate orange rootstock.

The inocculum is introduced only once into the mother tree, the one that will be sources of budwood before propagation.