Hi, Katie!
Great question!
Your
Disney Dining Plan entitlements are all placed into an account which is much like a bank account: it gathers all of your entitlements into one place, so that you can see what you have to spend throughout your trip.
We have sometimes had extra Table Service or Quick Service entitlements while touring Walt Disney World, and have decided to try an additional set of dishes among our party, just for the fun of it (plus, we had the entitlements to spare, so why not?) As such, you should be able to tell your server that you'd like to use more than one Table Service entitlement so that you can sample more than one entree / dessert. Keep in mind that your under 3-year-old is welcome to share from your plate so you won't have to worry that the youngest one is at a disadvantage.
Keep in mind, too, that you can visit a Signature Dining Restaurant (which take two Table Service entitlements) or visit TWO Table Service Restaurants in one day (enjoy an early breakfast and dinner, for example, saving your Quick Service entitlement for the day of your departure.)
These credits are all placed into your pool of entitlements, Katie, so you may use them as you wish throughout your stay.
Send more questions as you think of them; we love to help!