Building site on another domain name

Hello,

I am building a site on one of three domain names that all point to https://www.aframesb.com

I am updating it from an old SBI site (the https://www.aframesb.com) We have 2 other names that all point towww.aframsb.com: aframe-paint-booths.com; paint-booths.com. In order for me to keep the current one up and running while I build the new one, I needed to start building on one of the other domain names for some reason. There was no temp site option to build on. I am also building it in the blind because when I login to admin to make changes, then “visit site” to see the changes, it goes to the current SBI site: https://www.aframesb.com

Will I be able to eventually redirect everything to the new WP theme which I am building on aframe-paint-booths.com? Or do I need to stop where I am and not waste anymore time because I will end up having to rebuild it later on the main domain name? I hope you can understand what I am trying to convey. It is rather convoluted because I don’t really understand what I am doing!

Thanks in advance,
Kirsten