Oh, this is totally the nesting instinct talking! It's hormonal and very real, many mums feel this sudden urge to nurture and prepare their space as they get closer to baby time, so wanting another cat makes complete sense. That said, I'd be honest with you: adding a second cat right now is probably not the best timing, especially with your senior boy and a newborn coming. A friend went through the same thing and held off until three months after her baby was born, and she said the hormonal fog cleared by then and she was grateful she waited, the energy to manage multiple cats alongside a newborn was just a lot more than she'd imagined. The nesting feeling will pass, and your senior cat will likely appreciate the calmer household when baby arrives. If the urge is still strong after a few months postpartum and life settles, you can always revisit it then when you're in a better place to judge what's right for your family!