Method to manufacture a container includes disposing a first parison within a first mold assembly having a first inner surface defining a first mold chamber. The first mold assembly includes at least one first insert disposed on the first inner surface within the first mold chamber. The first parison is blow molded to form a first container body within the first mold chamber, wherein at least one first portion of the first container body corresponding to the at least one first insert has a first portion temperature greater than a remaining portion of the first container body. The at least one first portion of the first container body can be contacted to at least one second portion of a second container body to attach the first and second container bodies. Assemblies, systems, and intermediate stage pre-assembly multi-chamber containers are also disclosed, as well as multi-chamber containers formed from the same.