Are there any problems when updating resource labor hours and non-labor cost resources that are assi

We have a cost-loaded schedule that uses a lump sum, non-labor resource. This project has been going on for two years and will last one more year.

I've been asked to add labor resources to the remaining activities so we can see how many man hours the various trades take to perform the activities.

I know how to setup the labor resources and assign them to the activities.

I guess as long as "Calculate Costs from Units" isn't checked there shouldn't be any problems with cost.

Are there any problems when updating resource labor hours and non-labor cost resources that are assigned to the same activity?