Pete Wentz and Megan Camper Bronx

Fall Out Boy Pete Wentz is getting serious with girlfriend Megan Camper -- in fact she's more and more like a step-mom to Pete's son Bronx!

While mom Ashlee Simpson is off promoting her clothing line with sis Jessica, Pete is on daddy duty and Megan's pitching in, in her maternal role.

Could these two be looking to start and expand their own family together anytime soon???