I wouldn't use Send My Bag in this case: a move--yes, but a vacation--no.
First, I just had coffee here in France this morning with a woman who moved here and used Send My Bag for five boxes. Three arrived but two boxes have been sitting in French customs for three weeks. She has no idea when they'll be delivered. When I moved to France, the one suitcase I sent with Send My Bag took a week though it was scheduled for 3 days; I think it was the big jars of Costco vitamins that held mine up. OTOH, some arrive in two days.
Second, she would need to be careful about to whom the bag is addressed: if the daughter's name is on it and if she's been a Spanish resident for over year; she'd have to pay duty on the contents. We have stories of 40euros customs charges on 10euros gifts sent. It's crazy.
People who want to know their suitcase's location, put an Apple Airtag inside their suitcase and monitor its progress.