RailFans - हमको देख देख दुनिया जले, हमको ज़माने से क्या

Friends,
I need help....I am trying to book a ticket for 12617 ( MANGALA LDWEEP ) from ERS to MAJN....the search does not give me any option to book on this train in 3AC (not Available) but gives me 4 tickets for SL class.
But if I try booking the ticket from ERS to PNVL, then i have lot of tickets available for booking in both 3A and SL class.
Is...
more...

there any restrictions in booking in this train?
Also if one family is travelling together but half of them wants to get down in MAJN and other half in PNVL...how can we book the tickets and make sure they are travelling in same coach if not the seats are together.
Shaji