Launching Performance Goal Plan

Summary

Launching performance goal plan with one goal in it that is not 100%

Content

I wish to launch a goal plan with one goal in it with a weight of 10%.  However, I want employees to add their own goals to the plan, with a total weight of all goals to be 100%.  Is there a way I can do this?  I keep getting an error that the goals must equal 100%.  I do not want employees to have the ability to update the one planted goal.