Simulated child site to true child site conversion strategy

I have just successfully converted a 2.92 blog to a 3.0 multi-site blog. (Thanks for your help.)

I have four other sites that are organized into physical directories. They are 2.92 and 2.93 sites.

e.g

http://www.MonBed.com currently redirects to http://www.max-opp.com/monbed

http://www.alanjordan.com currently redirects to http://www.max-opp.com/alanjordanblog

Is the best procedure for making them 3.0 child sites to create new child sites and then to import the data?

If I do that, do I need a virtual directory name that is different from the physical directory name?

Also, if I do this, will it break existing permalinks? For example, what will happen when someone goes to http://max-opp.com/monbedblog/why-buy/parenting-tips-teaching-your-toddler-to-read

Thanks.