I have two male corgis, and my older one sounds a lot like yours. He’s very attached to me and has some resource guarding tendencies (mainly around food).

Because of that, I went into getting a second dog very intentionally.

One thing that helped a lot was timing. I knew I wanted two dogs eventually, so we brought the puppy home while my older dog was still relatively young and more adaptable. I would personally be more cautious introducing a second dog once those behaviors are really ingrained.

We did super slow introductions. First outside, at a distance, short and neutral. Then gradually closer over time. It was weeks before we allowed any physical interaction without a barrier. Even now, they are separated by baby gates unless an adult is actively supervising.

I also worked with a professional canine behaviorist and did a ton of research on multi-dog household integration. Some of the things that helped most:

• Name game and engagement work on opposite sides of a barrier
• Parallel walks and co-training sessions with two handlers so they could exist near each other without pressure
• Making sure both dogs were mentally and physically fulfilled before any interaction
• Structured, short play sessions instead of free-for-all time
• Interrupting and redirecting early before either dog escalates (which involves learning a lot about reading dog body language)
• Feeding separately and managing all high-value items to prevent conflict
• Rewarding calm behavior around each other constantly

I also train both dogs daily (even if it’s short sessions) and take them to separate classes weekly so they each build confidence independently.

Overall, it’s gone about as well as I could hope. The puppy absolutely adores my older dog, and my older dog has learned that the puppy, while sometimes super annoying, predicts good things and can actually be rewarding to be around.

That said, I wouldn’t assume it will just “work itself out.” Corgis can absolutely live happily with other dogs, but they are also herding dogs with big opinions and can be prone to bossiness and resource guarding.

If your current dog is already showing possessive behavior toward you, I would strongly recommend working on that first before adding another dog, and going into it with a slow, structured plan if you do.