  We report on the investigation of periodic superstructures in twisted bilayer
graphene (tBLG) van-der-Waals heterostructures, where one of the graphene
layers is aligned to hexagonal boron nitride (hBN). Our theoretical simulations
reveal that if the ratio of the resulting two moir\'e unit cell areas is a
simple fraction, the graphene/hBN moir\'e lattice acts as a staggered
potential, breaking the degeneracy between tBLG AA sites. This leads to
additional band gaps at energies where a subset of tBLG AA sites is fully
occupied. These gaps manifest as Landau fans in magnetotransport, which we
experimentally observe in an aligned tBLG/hBN heterostructure. Our study
demonstrates the identification of commensurate tBLG/hBN van-der-Waals
heterostructures by magnetotransport, highlights the persistence of moir\'e
effects on length scales of tens of nanometers, and represents an interesting
step forward in the ongoing effort to realise designed quantum materials with
tailored properties.
