They are both in active use and one produces literature and sells it to the other for distribution but I cannot remember which way round it is.
WTBTSB Accounts 2014....
Income...
Producing and distributing Bible literature 8,759,227
http://apps.charitycommission.gov.uk/Accounts/Ends61/0001077961_AC_20140831_E_C.pdf
IBSA Accounts 2014....
Expenses....
Provision of literature for Bible education 8,820,956
http://apps.charitycommission.gov.uk/Accounts/Ends47/0000216647_AC_20140831_E_C.pdf |
WTBTSB sells the literature to the IBSA.