Assuming typical (ish) boil off rates, no mashtun loss, you should be looking at around 67-70% lauter efficiency (so your remaining grain bed would be approximately ~6.6 lbs of grain), for a no sparge 22lb grain bill with a 0.08 gal/lb grain absorption. If you're not squeezing, then drop that down to ~63% (~8.15 lbs of grain equivalence remaining).

By using lauter efficiency, and equivalent remaining grain, it's easy to throw that amount into a new recipe rather than using a gyle calculator and then a blending calculator and then adding additional new recipe to add onto it. Just remember to adjust your water volume, as the remaining equivalent grain will not absorb additional water (unless you squeezed for first runnings, but won't on this second brew).

Predictions made using my software, which is based on braukaisers model, but much simplified with negligible loss in accuracy 0.02%.