subnect
To (literally) tie or fasten beneath, or to (figuratively) join beneath, i.e. as an addendum.
archaic, transitive
his robe might be subnected with a Fibula
Where it comes from
From Latin subnecto, from sub (“under”) + necto (“to tie”).
Adapted from the Wiktionary entry subnect (CC BY-SA 4.0).