How does she know Louise?
She and Louise have been friends publicly for about 3 years now. Louise did a speaking event for Channel Mum with Giovanna Fletcher around that time. I think that's how she met most of them. Louise has worked with Emily Norris, Rebecca Meldrum, Katie Ellison, and Emma Conway (BrummyMummy) on a few occasions. She actually used to be really close with Emma, but they haven't mentioned one another on camers for quite some time.
Katie and Louise are such an odd pairing. Yet, it seems genuine. Louise has had several high profile YouTube friendships during her 10 + years, the longest being Zoella. Once Louise rebranded, she started acquiring more mom friends. I've heard Louise mention possibly becoming a media consultant for public figures when she stops YouTube. Perhaps that's why she and Katie are friends.