Credit Card 1 (Legally on LLC 1's name)
Under LLC 1 Books: Post them under Due to/from LLC 2
Under LLC 2 Books: Post JE - Debit (Expenses) and Credit (Due to/from LLC 1)
Credit Card 2 (Legally on LLC 2's name)
Under LLC 2 Books: Post them under Due to/from LLC 1
Under LLC 1 Books: Post JE - Debit (Expenses) and Credit (Due to/from LLC 2)
In both cases personal expenses will be posted to Shareholder Loan Account