We just jumped into 3 yorkies last week with the addition of our foster Shelly. It has been quite the change. We take our two everywhere, and they ride in their Kwigy Bo bag. Adding a third definitely put a hitch in that because three definitely will not fit in the bag

We have still taken her along (we usually are at pet friendly places), and she is doing well.
Luckily all three of mine are getting along, so that hasn't been a problem... But you have the increase in vet bills, grooming time, and food.
My advice would be to keep to a schedule; make sure they are getting out to potty regularly, eating at the same times, etc. This will help your transistion and your dogs will appreciate it