Re: Can Bmi check thriugh luggage?
The airline can say no to you, as you have two separate tickets. Note, if you arrive late in LHR, BMI can refuse to honour your onward ticket, as it is bought separately.
There is usually a charge for interlining (for the convenience of having your luggage through checked, onward boarding passes, and a guarantee of getting your onward flight or the next best alternative).
Still, it doesn't hurt to ask at check-in in Dublin!