You have the option to set multipet pet rates for runs so that you can offer discounts to pets of the same family.

Click on File, Lists, Run Sizes.

For each run size, enter rates for up to 5 pets.  Rate is for the 1st pet.  Hit Save after each run size.

Please note:  If you do not enter a rate for pets 2 - 5, then KC will charge the first pet rate.