Dual Divine Theurge?

[Scrapheap]

I know there is the Ultimate Magus that combines Wizard/Sorcerer style casting, but is there anything similar for Divine casters?
Something that would let you take both Cleric and Favored Soul for example?

[Anthrowhale]

Mystic Theurge a Sha'ir/Cleric?

Or Green Whisperer Bard/Druid with a divine bard variant.

[Thurbane]

I know there is the Ultimate Magus that combines Wizard/Sorcerer style casting, but is there anything similar for Divine casters?
Something that would let you take both Cleric and Favored Soul for example?

It doesn't have the same support that Ultimate Magus provides for arcane, no.

The Savant from Dragon Compendium has (limited) arcane and divine casting, so you could theurge that with Cleric or another divine class.

I feel that a Cleric/Favored Soul is going to be pretty redundant, though. You'd be getting some extra spells/day at the cost of caster levels. Basically Anything a FS can do, Cleric can do better.

You could also look into the Southern Magician or Alternate Source Spells feats...

[Psyren]

Best I can think of is Skypledged, with a spellpool (similar to the MotAO) that lets you draw from both the druid and cleric lists. I'll echo Thurbane though, there's basically zero benefit for theurging cleric with FS. With Wizard/Sorc it kinda makes sense since neither class natively gets all the spells on their list, and you might have a DM that is stingy with scrolls - but Cleric doesn't have that problem.

[Selene Sparks]

Also Clerics have native access to what is generally the real draw of Ultimate Magus anyways, which is metamagic shenanigans.

That said, you could take Rainbow Servant on any arcane caster to 10, and then take Mystic Theurge on Cleric or Favored Soul, depending on which you'd rather. It'd be less efficient, but if you're going Beguiler 1/Rainbow Servant 10/Cleric 1/Mystic Theurge 9, you'd look pretty much like what you seem to want, even though the secondary casting is pretty much superfluous outside of some domains and, of course, turning.

I think the real question at hand here is what, specifically, are you wanting to accomplish?

[Rebel7284]

Archivist?

[Venger]

there's always southern magician