Macro and select multiple values from Dropdown

Sorry if this is a repeat. I read through many posts and do not see the same exact question. I am familiar with the generals of excel, but not when it comes to macros.

First my pulldown list question. How can I allow users to select multiple values? They can only select one, but, for example, I may need them to select four names from the pull down list. There are no actions following that.

Now for the macro. I want to create a macro that when X number rows are manually added to tab CC, that
- Column A from tab CC is copied to Column A on tabs AA and BB.
- For the new rows (X) on tab AA that now only have column A filled in, copy columns B-U (the vlookup functions) on tab AA to the new rows (X) on tab AA.
- Repeat the step for tab BB, for columns B-K.

I can't send the worksheet because it has sensitive information.

Thanks in advance so much!!

Tamara