Industry rule now
This is now an industry rule - although interpreted in different ways/
For your curremt route - you WILL have to collect your bag in FRA - it is sensible also as TG operate from a different terminal.
However - if you changed your booking to LH or BD - you would be able to check them all the way through - as if your flights are all Star Alliance - they overlook the twp ticket rule.
Also note - if it is an e-ticket - BD does not allow ANY interline of baggage!
goof luck!