Oblivion is NOT associated with multiple princes.
Sheo etc do not have a plane of Oblivion, the planes of Oblivion belong to Mehrunes Dagon, and only Dagon.
oops?
Each Prince has his/her own Plane = plane(t) - if fact the Prince is the Plane(t) ...
a plain on which you found a tower is just a plain old plain - like a prairie ...
According to a text found in the game/Oblivion:
A sigil stone or morpholith is prepared/consecrated in an Arcane ritual in a specially constructed building during an equinox somewhere on Nirn.
Then whoever prepared/consecrated it - the mechanic - takes it to a Daedric Prince who then inscribes a Rune on stone empowering it.
to Open a Gate
The mechanic at any time thereafter must communicate with the Daedric Prince who inscribed the stone and together they invoke a charter/agreement/perform a conjuration together at which point the sigil stone then returns to the place where it was originally prepared/consecrated and a gate opens between that place and the location where the Prince and mechanic are conjuring from.
end of translation.
However this is interesting in that it appears that for Oblivion the process was different - there is no way that a building was constructed in Kvatch to prepare a sigil stone - so one may assume that either the writer only understood part of things and he was just a beginner and had a lot to learn or there are other books that talk of variations on ways to create Gates or maybe there was a lot more in that book that was not legible.