You don't need any wave component to do this.
Only you need :
read wave streams byte by byte. and merge how you want.
for example 8 bit 8 waves we have, let's calculate first byte of mixed stream:
if no signal, byte is 128 (dc level, electronics term
). Therefore we must decrease '128' from all bytes before processing. Theese results are signed values .
bytemixed0 = (byte7_0-128) + (byte6_0-128) .....(byte0_0-128)
ok. we must add 128 again our mixed signal
bytemixed0 =bytemixed +128
if you have 16 bit waves, this methot may be easier . Becouse, zero level is 0 for 16 bit waves.