I don't see why not. Have his Dad call Pioneer high school and register him if he lives with Dad more than 50% of the time, then Dad's address should be used as Son's residence. It would be as if Dad had just moved to the area with Son. Unless Pioneer is considered "overcrowded" there shouldn't be a problem. I would just have Dad call them and say "I live at this address and I need to enroll my son". Pioneer can request his transcripts from Willow Glen. If you want to get the phone number for Dad to make it easy for him, you can go to http://www.greatschools.net to look up Pioneer's phone number.
Hello Mrenneke, I have a link on my website for schools. Go there and look up the district information. Give the district a phone call. If you child lives with his parent for most of the year I don't think it would be a problem, but the district would be the one to give you the answer. Good luck.