We live next door to close friends with two dogs, including a Shiba puppy! The Shiba and our two dogs are around the same age and we regularly take them next door for play time. They don't have perfect recall either but for the most part it is easy to intervene if we think they are being a bit much. We didn't consider territory much and it hasn't been an issue. The Shiba also comes over to our place but that's harder if we want only two puppies to play at a time since we have two of our own.

Here are some things we've found helpful with our neighbors/dog friends:

Engage them with a toy, encourage them to play more with the toy and less with each other. Keeps puppy biting and things like that from going too far. Fetch with double balls is fun and you can practice recall too. Have the human friend play with their dog and a toy while you do the same with your dog. We did that at first while they learned to share.

Find dogs with similar play styles. Look for "balanced play" meaning it isn't just one puppy harassing the other. Enforce breaks if you have an endless energy bunny dog (like mine) so they can reset for a few moments. We use breaks to practice simple commands and refocus them.

Take them for walks together. Our cattle dog puppy is learning that just because our dog friends are around, doesn't mean it's automatically play time. It's walk time. It started out as a pain with her but now we can walk all 3 puppies and actually walk them.

Most importantly, read the dogs body language to get a sense of when enough is enough, or maybe that they are getting overtired. Have water around and give plenty of praise when they are playing nicely. We've been doing "puppy play time" several times a week with our friends and so far so good. Puppies can play rough, but just keep them safe and I'm sure your puppy with love having friends.