H4 questions, please help

LG changed employer last year and changed his H-1B from university to industry. That time the company lawyer said (last year) it is ok to renew my and my son's H-4s later when the H-4 close to its expire date. We decided not to change our H-4s until half year before the expire date. But the problem is ou H-4s have different expire date with my LG's H-1B. Is that a problem?! We are kind of anxious about that. Please give your kind advises. We sincerely appreciate it.

Thank you so much, and wait on-line......