[SR-Users] Need help to send INVITE to multiple client based on REGISTRATION status

Hi All, Following are the requirement which we want to achieve through Kamailio. Our "voip client" will not be register in advance.When Kamailio get INIVITE request for particular "voip client"(multiple client), we send push notification to make "voip client"(multiple client) alive and get it register for to Kamailio. Meanwhile INIVITE request will wait. the moment, "voip client" get register, Kamailio will send INIVITE to all the client despite their *registration time/status*.for example - if first client get register with in T+1 second,that should also get INVITE and another client get register in T+2 second that should also get INVITE. Could you please help me if this is possible in Kamailio. I have done some code walk through and have the basic idea to save the INVITE transaction(similar to suspend and continue), later point of time when i get the register request, I will use functionality like t_lookup_request and and lookup(which in turn append_branch) and call the t_realy () again. Please let me know if this is correct approach or if there is some other way to solve this. Thanks, Amit