  Observations of protostars are often compared with synthetic observations of
models in order to infer the underlying physical properties of the protostars.
The majority of these models have a single protostar, attended by a disc and an
envelope. However, observational and numerical evidence suggests that a large
fraction of protostars form as multiple systems. This means that fitting models
of single protostars to observations may be inappropriate. We produce synthetic
observations of protostellar multiple systems undergoing realistic,
non-continuous accretion. These systems consist of multiple protostars with
episodic luminosities, embedded self-consistently in discs and envelopes. We
model the gas dynamics of these systems using smoothed particle hydrodynamics
and we generate synthetic observations by post-processing the snapshots using
the \textsc{spamcart} Monte Carlo radiative transfer code. We present
simulation results of three model protostellar multiple systems. For each of
these, we generate $4\times10^4$ synthetic spectra at different points in time
and from different viewing angles. We propose a Bayesian method, using similar
calculations to those presented here, but in greater numbers, to infer the
physical properties of protostellar multiple systems from observations.
