A single Okie story became the concluding fourth section of Earthman, Come Home which became Volume III of the Cities In Flight Tetralogy which, in turn, was collected in a single omnibus volume.
A single pantropy story became Cycle One of Book Three of The Seedling Stars, a single volume.
A single theological sf story became Book One of A Case Of Conscience which became Volume III of the After Such Knowledge Trilogy, eventually collected in a single omnibus volume.
A single Haertel overdrive story became the basis of the Haertel Scholium which includes A Case Of Conscience.