“Partial” graph layout (with a fixed core)?

Is there a way to apply a graph lay out algorithm to a Graph object in such a way that a subset of its vertices and a subset of its edges are fixed beforehand, and their positions/shapes remain unaffected by the algorithm?

• Could you come up with an example of a Graph and the output you would expect? – Öskå Nov 4 '14 at 14:10
• igraph's DrL layout generator has this feature and I'm working on an igraph interface for Mathematica. However, I did not yet expose this option because I got very disappointed with the results I got from DrL. I could never get it to look good on fairly simple graphs. – Szabolcs Oct 1 '15 at 17:40