What are the Ohms of each speaker?
If dual 4 ohm and single 4 ohm - the amp I guess can handle 2 ohm load?
4+4=8 (series together) and put the 4 ohm in parallel you should be OK
Failing that as the amp may not handle 2 ohm,
Parallel the Dual to give 2 ohms and series in the 4 ohm speaker to give 6. Amp should def handle that but power will be down a bit
Series the dual voice coils, gives an 8ohm load. Run parallel with the 4ohm single voice coil will give a total of 2.67 ohm. That's fine as most mono amps are at least 2ohm stable, the better amps are 1ohm stable. The only issue will be the dual voice coil kicker will be an 8ohm sub, so won't see as much power as the 4ohm sub, so will be not as loud comparatively.