change permalinks for 2 specific posts

I wish to rewrite permalink in th efollowing way (just for two specific Pages):

1) there are two pages: mypage.com/byindustry & mypage.com/bystyle

2) I wish those to be rewritten (or if not rewritten then to have also ‘second’ permalink) :

mypage.com/byindustry would be the same as mypage.com/portfolio/byindustry & mypage.com/bystyle would be the same as mypage.com/portfolio/bystyle