ABOUT YOUR PROJECT: It sounds a little like you're looking for something like WordPress "multisite". It's one database, one set of registered users, but two separate websites with shared themes and plugins. They can use different themes, but they're all managed from one WP admin page. I built (and maintain) a WP multisite installation with four separate sites and four domains. Look at the martial arts samples in m portfolio. They clearly are "kin", but have their own personality. If that's what you want, I'm your guy!
ABOUT ME: I am a Midwest USA based WordPress designer and IT professional, with 25 years experience.
I look forward to talking with you about the specific needs of your website and developing a project plan and timeline.
The portfolio in my profile on this site shows examples of my website design work.
(If you're new to Freelancer.com: Milestones are a kind of escrow system. You don't release money to me on a milestone, you pay Freelancer and they hold it in escrow until we agree the work is done. It protects both of us!)