Hi! I have a 7 month old kitty, Lilly, and our new addition Gerald who is 2 months old. Lilly weighs over 5 lbs and Gerald was 2.5 lbs at his last check up. We just purchased a 6 pack of Advantage II for the kitty's for flea preventative. However, the weight for the pack is 5-9 lbs, obviously Gerald is not 5 lbs, but I didn't want to buy two different packages of flea medicine especially when he won't stay 2.5 lbs for long. Is there any way to still give him a proper dosage with the 5-9 lb advantage I bought??? Thanks in advance!!