Twin T Drums (Practical Electronics 1978)

your module should work even without the addition of Sam’s part of the complete module (even if personally I added it to my stripboard and recommend it)
and yes if it does not work individually in my opinion there is no chance that it works mixing together (since it is taken from each signal output)
maybe use the complete schem to check all this (this is what helped me to better understand the circuit and correct my errors)

and maybe take a look here too