  An extended $1$-perfect trade is a pair $(T_0,T_1)$ of two disjoint binary
distance-$4$ even-weight codes such that the set of words at distance $1$ from
$T_0$ coincides with the set of words at distance $1$ from $T_1$. Such trade is
called primary if any pair of proper subsets of $T_0$ and $T_1$ is not a trade.
Using a computer-aided approach, we classify nonequivalent primary extended
$1$-perfect trades of length $10$, constant-weight extended $1$-perfect trades
of length $12$, and Steiner trades derived from them. In particular, all
Steiner trades with parameters $(5,6,12)$ are classified.
