Depends on how you add the external money. When you do a large investment at one point, you can increase the margin in proportion. When you however add the external money step by step, like some small amount every month, the rule to increase the margin only by the square root of the account growth also applies for adding money from outside sources.

I believe you can not trade standard 100K lots with the free Zorro version. The $7K account limit is too small for standard lots.