[yocto] adding task before a task T but after all other tasks that T depends on?

[Ulf Samuelsson]

Is there a way to express this?

Assume three classes X,Y,Z, each adding a task.
X: addtask x after S before T
Y: addtask y after S before T
Z: addtask w after S before T

Images might inherit one of the classes X,Y,Z.
Thus x, y, or z might run, but only one of them, and which depends on the image I build.

How do I add a task z, which runs after any of x,y,z, but before T?

The list of possible tasks might be extended in the future, so I really would want to
specify:  ”addtask w after T[depends] before T” or similar.

Best Regards,
Ulf Samuelsson