Insurance company guidelines differ so you will need to check with your auto insurance provider to find out if you will need to add your 16 year old licensed daughter to your current policy or if being on her mother's (the custodial parent) policy is enough.
It will likely depend upon how often your daughter uses your vehicle and what the specific terms of your current policy state. It may be that she will need to be added as an occasional driver or that she is covered already under your policy if you loan her the vehicle. Again, check with your insurance agent and they will be able to tell you the guidelines your insurance provider has in place and if she is covered or not for operating your vehicle.
If you find out that you need to add her to your policy and want to comparison shop for rates, start here by getting an affordable insurance quote.