Secondary apperance, color-scheme and menu.. is there any way I could do that ?

Hello,
I need to do a secondary site for a client.. basically it’s a dance school and the secondary will be like a completely different section targeting other users.. However a lot of the info will be the same, for example teachers’ profiles.. so it would be good that those can actually be shared.. and thus in the same site.. even if the look has to be different.. I cannot quite think of how I could achieve this.. Any idea ?

This looks like something that could help me, but it scares me a bit ;0)
https://wordpress.org/plugins/jonradio-multiple-themes/

H E L P :0)