Users affiliated with a first narrowband talk group or participating in a narrowband talk group communication are able to establish a parallel communication group with the same users of the first talk group using alternate communication devices to enable transmission of multimedia over the disparate communication networks. One or more databases store and correlate information regarding the users of the narrowband talk group, as well as information regarding the user's communication devices and access technologies employed by the communication devices to determine the possible broadband groups available and an acceptable access technology to transmit the multimedia to the broadband group/data group users. The disparate network group manager informs the users of the narrowband talk group of the presence or availability of the parallel broadband group and establishes the parallel broadband group session when requested to do so by a user of the narrowband talk group.