Introduce a new cat to your existing pets gradually. Start by keeping them in separate areas, allowing them to get used to each other's scents without direct contact. Swap bedding or toys between the new and existing pets to familiarize them with each other's scent. Gradually introduce visual contact through a baby gate or cracked door. Supervised, brief face-to-face interactions should follow, gradually increasing in time as they become more comfortable with each other. Use positive reinforcement, like treats and praise, to encourage calm behavior. Patience and slow introduction are key to a successful integration.