I already outlined a model setup: express the relationships among Tasks as equations, and apply the constraints as min/max limits. You would need to switch to Evolutionary engine, since the problem is now non-linear.

More importantly, Solver has a limit of 200 on the number of decision variables, and we have approximately 525 binary vars (35 Tasks x 15 Persons) and 35 integer vars. Usually, extrapolation doesn't work very well in this kind of problems.

However, it may be possible to linearize the model and then use OpenSolver, a free Add-In that has no limits on the number of variables.

HTH,

Francesco