multiple cells - single layout

Hi,
I have 3 cells with each their own lib-model. Since the layout of the combination of these 3 cells is very critical, I would like to use a single layout for the combination of these cells.

So in my netlist I would have something like this:

CELL1 u_cell1 ( Y, A, B)

CELL2 u_cell2 (X, C, D)

CELL3 u_cell3 (Z, E, F)

But In layout I would like to use a single cell CELL123(X, Y, Z, A, B, C, D, E, F). Making a single lib-file for this cell is not feasable due to the timing dependencies between A, ..., F

Anyone got any advice on how to handle this?

Kind regards!