Hi,
Yes that’s correct. Once you export the universe in repository then individual business layer will associate with individual data foundation layer. Any change in the associated data foundation layer will reflect in the business layer. Let say two business layer A & B are depend on the data foundation layer C and business layers A,B are exported to repository then two individual DF layers C are associated with A & B. If you will again import the universe A and then do some changes in the DF layer C then these changes will reflect only in business Layer A not in the B.
Amit