Some neutered males still take an interest in bitches. William, 10 years old and castrated at 15 months, is mildly interested and likes to have a slightly impolite sniff every so often, but that's the extent of it. Strangely enough 5 year old entire Louis seems completely unaware
. Knowing that William is mildly interested I wouldn't want an in season bitch to stay with us in case the constant presence made William more excitable
and trouble broke out.
Friends of mine had a neutered male Border Terrier, a neutered male Corgi and two entire Border Terrier bitches. The Border Terrier dog had to be sent away to stay with friends each time the bitches came in season because he would try mating with them and was a real sex pest throughout their seasons. The Corgi didn't try mating but became very defensive if other dogs were around, although he was a bit like that anyway.
I think there's no way of knowing how the Westie will react to Wilma, or her to him, but if you take Wilma with you I think you should be prepared for possible sex pest activity from the Westie and flirting or a negative reaction from Wilma. Hopefully nothing like that will happen, but just be aware that it could. It would be pretty horrible if Wilma and/or the Westie were stressed all weekend and ended up hating each other for ever.