think in your case you can use Parent like here:
http://demo.aspnetawesome.com/MultiLookupDemo/Misc#MultiLookup-bound-to-many-parents
with ParameterFunc you set the name of a js func that will return a json object like here:
http://demo.aspnetawesome.com/PopupDemo/Index#Sending-client-side-paramters-to-server-on-content-load
http://demo.aspnetawesome.com/MultiLookupDemo/Misc#MultiLookup-bound-to-many-parents
with ParameterFunc you set the name of a js func that will return a json object like here:
http://demo.aspnetawesome.com/PopupDemo/Index#Sending-client-side-paramters-to-server-on-content-load