Scottish urban-fantasy slice of life series -- girl and her siblings(?) gain witches as parental figures(?)

okay, so was just reminded of this by a different ask that turned out to be something else but I remember reading this series of books as a kid/teen, sometime in the 2000s or 2010s. things i remember:

• so i think the plot revolved around a girl whose widowed father was dating(?) a witch or something? Idk i feel like there was some dynamic like that but i also feel like there were multiple witches of equal importance and it wasn't a polycule so maybe they were just friends or something. Or just one of them was dating the dad and the others were being supportive of her and coming along to watch the kids or something.
• maybe the group of women weren't witches, they might've been kelpies or something? They were somehow magic or mystical, or the mc thought they were.
• magic wasn't really a Widely Known part of the world iirc it was mostly just our world except magic is secretly real. I think i maybe remember a plotline where the main characters were trying to keep the witches from being found out by like. The police or the news or something
• there were maps at the start of the book and the maps labeled all lakes as "loch" which i think was how i realized that loch was scots for lake and didn't just apply to loch ness
• There was also a scene i definitely remember where it mentioned one of the mc's friends(?) being denied "pudding" and them holding a protest about it, and I had to do some googling to find that apparently brits use "pudding" to mean "dessert". I remember an illustration where one of them was holding a homemade picket sign that abbreviated it as "puds" or "pudds"
• this wasn't a picture book, it was a chapter/middle-grade/ya book that had occasional pen/pencil sketch-looking illustrations.
• I think the author was also the illustrator but i could be wrong?
• set in Scotland and the author was almost definitely Scottish