I don't have a soccer ball ,but my brother Alan does 为什么不是Alan has.

I don't have a soccer ball ,but my brother Alan does 为什么不是Alan has.
I don't have a soccer ball ,but my brother Alan does 为什么不是Alan has.

I don't have a soccer ball ,but my brother Alan does 为什么不是Alan has.
I don't have a soccer ball ,but my brother Alan does 为什么不是Alan has.
为了避免重复,常常用【代动词do/does】来代替【实意动词】.

因为主句中have是作为实意动词使用的，然后前面加了助动词do，那么在从句中，自然是用does第三人称来替代了
希望对你有帮助哦~~