How can I purchase series fares for Lcc and Gds airlines?

I am running travel agency and I have IATA accreditation but,mostly I am doing bookings through b2b portals? How can I buy series fares If I don't have direct connects with airlines?

And if I have recently integrated gds I have just 26 airlines ticketing authority on my IATA bsp how can I increase that number and get ticketing authority of other airlines as well?

Also,if I am creating pnr on my gds and importing it to any agency will that be considered as my issues ticket or that agency's issued ticket?