Going one or two tables is a common issue, there are usually pros AND cons, and the right solution depends on the individual case.
What you have figure out is what criteria determines the right solution!
-Simplicity of data?
-Number & Simplicity of SQL calls?
-Number of records in a table?
-Possibility of the more data/columns being added in the future?
Will that future data be common or not?
- etc...
I would write down all the pages you will have, and for each page the SQL calls you will make, and figure out if they will be easier and faster using one or two table schema. For example, a search on two tables is more complex than just on one. But is this the ONLY page where you hit both types of records?
If using one table, just add a column called for example regType, 1 or 0. (1=group, 0=individual), and add that into your SQL statements. It is ok to have some blank columns, which only get used for their own regType.
Have fun!