  The obvious way to construct a GDD (group-divisible design) recursively is to
use Wilson's Fundamental Construction for GDDs (WFC). Then a PBD (pairwise
balanced design) is often obtained by adding a new point to each group of the
GDD. However, after constructing such a PBD, it might be the case that we then
want to identify a parallel class of blocks. In this short note, we explore
some possible ways of doing this.
