One step forward, three steps back

I began a new project on the second floor landing and, after pulling down the wallpaper and sanding the walls, ran into  problem.  What a surprise.  It seems that the ceiling was plastered around the crown molding, i.e., rather than taking down the crown molding, plastering, then putting it back on, they skipped step 1.  We pulled a small piece off, leaving a big hole.  So now what?  Do we redo the whole thing, once more?  Do we do a quick and dirty fix and leave the real fix for another time?  How many projects can we launch at one time?

This is a little discouraging, at times.