We study the problem of scheduling $n$ similar jobs on $m$ machines, with respect to the fact that jobs are dependent and some of them must be performed before others. Dependencies between jobs are modeled as a partial order relation. Machines are prone to crashes, induced by an Adaptive $f$-Bounded adversary who can fail up to $f$ machines, where $0\leq f < m$. Communication takes place via a Multiple-Access Channel (MAC), which restricts simultaneous transmissions. We show an optimal solution (with respect to total work of all machines) for partially ordered sets of jobs forming chains and an algorithm and lower bound for trees.