If memory serves, Iceberg did a number of two- and three- LNBF C band experiments on his 6'er, several years ago.
Might be instructive to search for those.
Over the years, we've had many great discussions on multi-LNBF setups.
One member posted some simple equations to solve the problem.
I studied 'em and promoted their use many times for quite a few years.
One thing you immediately see, is that longer focal length dishes work better for close satellites.
And if you look at enough BUDs, you'll notice there are two kinds:
- deep dish, where the scalar is close to the dish rim
- shallow dishes, where the scalar is far skyward from the dish rim
The shallow dish would be a better candidate for multi-LNBF use.
As a rule of thumb, Ku dishes are more similar than different.
So, you go for a bigger dish to get a longer focal distance.
ie: a 1.2m is a better choice than .6m dish.