Baby girl names

Hi, I'm pregnant with my third boy. since I was pregnant with my second boy before I knew it was a boy i already had a girl name picked out. When we talked about it with my husband and his sister and her bf we were talking about baby names and I said I wanted to name my daughter alayna. well about a year later pass i got pregnant and I didn't know what I was having they asked me if it's a girl what would I name her i said alayna and my sister in law is like I wanted to name my daughter that ( she not pregnant) and I said I had that name picked out I even let you know but she said she didn't remember. the thing is if she has a girl before me can i still name my daughter that name even if she named her daughter that but spelled Elena. even though i feel like she stole it from me. ?