Slab Off Question+ prism splitting

[Rafael]

Have to make the following RX:

Bifocal C25

R: sph: -9,25 cyl -1,75 A: 67 Prism 5,0 B90 Add:2,0

L: sph: -4,75 cyl -0,5 A:30 Add:2,0


My Question now is, without the precsribed prism i need 3,95 vertical slab prism.

The Problem is the Blank thickness it will be not thick enough, so i would split the prism as follow:

R: 2,5 B90 + ( Slab off Prism)
L: 2,5 B270

or is it allowed to take the whole prescribed prism 5,0 B90 from the right lens, and put in on the left lens @ 5,0 B270.
And make on the right lens only the slab off prism.

Thank you