  We compute top quark pair production in association with a bottom quark pair
at the LHC within the five-flavour scheme, employing the FxFx merging scheme
for $t\bar{t}+\textrm{jets}$ production with up to 2 jets at NLO accuracy. To
enhance the selection efficiency for the events with $b$-jets within the
inclusive five-flavour sample, we augment the generation probability of bottom
quark flavours in the short-distance event generation. Our analysis reveals
significant differences from NLO predictions within the four-flavour scheme.
