Collecting Blish Series

OK. This is the way to do it (a "Why didn't I think of this before?" moment):

I. The Haertel Scholium Prelude: the early interconnected stories and the Galactic Cluster Trilogy.
II. The Heart Stars: the Jack Loftus novels.
III. After Such Knowledge.
IV. The Seedling Stars.
V. Cities in Flight.
VI. The Quincunx Tetralogy.
VII. The Haertel Scholium Coda.

Thus:

"Haertel Scholium" volumes would open and close the sequence;
the "Coda" would be read at the end where it belongs instead of in the opening volume;
"The Haertel Scholium" and "The Heart Stars" form a fortuitous verbal sequence;
the latter is an appropriate title for the diptych, The Star Dwellers and Mission To The Heart Stars;
The Heart Stars would also be a companion title to The Seedling Stars.