Adopted a new doggie and need advice.

Hello everyone, I just adopted a new dog. She is a an Australian Shepherd and she is 2 years old and non spayed. We got her yesterday and we are planning on getting her spayed later this week before she goes into heat again.

We have another dog already who is a 4 year old mixed breed who is spayed and we have had her

for 3 years! I know that bringing in a new dog can be an adjustment and they have already gotten along so well, they play a lot and have similar temperament when they play. We do live in a large townhouse and we did adopt the sweet girl from a house with a yard so I know it will take some adjustment for her to adjust to going outside on a leash. Does anyone have any advice on how to make this adjustment go as smoothly as possible? Once she is spayed and healed we are planning on taking her to daycare with our other girl and we are an active family. I just don’t want to let her down but I also don’t want our original girl to feel replaced at all.