so i have finish this game on hard casual and doing it 2 more time on lunatic and lunatic + on casual and i want to get my character from hard on lunatic how can i do that

You can't. Each save file is independent -- there's no New Game+ in this title.

Also, what's the point of playing on Lunatic mode if you're on casual? The entire point of higher difficulties in Fire Emblem is to make your playthrough pain.

well the point is i want to have all the future children and i heard that you can by doing the wireless renown character

also if i really want it to make it easy i would use a walkthrough or go on youtube and look a video to see exactly how to do it without dying