Now,Japanese name have 2part , " family name- own name". Maybe 海夜 is own name and you want make family name, right? As you know, every character have clear mean. Your name 海夜 is sea of night, and it sound very cool. 桃花 is always use own name for girl. And imadge is very cute. 花咲 use family name, it is not special name , I think. You can use those 2name, but I think more cool character is good to your name.

I think 桃花、海夜、are best.桃花pronunces ももか or とうか.and 桃咲pronunces ももさき. There are lots of pretty name for girls.For example,芽衣（めい）、花音（かのん）美桜（みお）、桃花（ももか）、桜子（さくらこ）. you can find lots of pretty names.

There are name we use both family name and given name. So if you realiy want, you can use 桃花 海夜. We don't row 2given name, but its OK. Stage name is free. 桃花 海夜 is nice. 花雪 海夜 はなゆき みや is nice too. I like 花雪 than 桃花. Both good. One technic to make nice name is using character which concern each other. Well, my one recomed is using character 月 つき. Because 月 concern both character 海&夜. In Japan 月 has very good image. For example, 月城 つきしろ moon castle 花月 はなつき or はなづき 華月 はなつき or はなづき 花 華 is same mean ,but 華 is more gorgeous. 星 ほし star is good,too. Technic 2 is use antnym. your given name is night sea. so, use morning image character. 朝露 あさつゆ morning dewdrop 朝霧 あさぎり morning misty No3 is using aristocratic name. ～小路、～河原、～条 etc... use like that 桜小路 さくらこうじ Well, most important is use your favorit character So, I think 桃花 雪花 is ＯＫ!!