I love Rosebeth for you. It’s a beautiful bespoke choice to honour those two important women from your families. I see it as a reimagining of two classic names with a strong reason behind it. It also feels like an old established name, forgotten along the way, as all of the letters feel like they belong. I’m reminded how so many names were formed this way throughout history by bringing two existing names or words together.
That said, I think you can absolutely give this child two middle names with a double-barrelled surname. It will be a long name, yes, but it’s the first name and surname that they’ll be using on a regular basis. The middle names will be out of sight for the most part, there for them to appreciate. A friend of mine has five names, three being middles. It hasn’t caused her any real life issues. You may also be interested in this blog post which includes the concern about giving a child a long name. So if you feel that Rosebeth would diminish the honour to both women, or if you feel that Rosebeth would receive strong judgement from your family, the length might be worth the compromise.
I also wonder if this baby is a boy, will you be able to find a Rosebeth equivalent for the middle names [name_m]Leonard[/name_m] [name_m]John[/name_m]? If you’re not able to combine honours for one gender, you could argue that as a reason not to do it for the other. If you decide that five names is a hard no, and Rosebeth doesn’t work out or you have a boy, you’d effectively be trading one of the honour names for the father’s surname. Would this seem like a fair trade to you, one you’re okay with? I’m not saying one way or the other, but I do think these are things worth thinking about.
It’s also a big change to make the baby’s surname to include the father’s. The order of the surname can make a difference too as it’s more likely for the second surname to be dropped than the first. It’s completely reasonable to take some more time to make this decision—especially when you have to consider the father’s future involvement with your child. I only say this in case you’re not entirely comfortable with the change. It sounded like a very sudden decision in your other post and wondered if perhaps you’re feeling a bit pressured to include it. You’re the mama, and I imagine you’ll be carrying the majority of the responsibilities. If there’s anything you’re unable to come to agreement on, I think it’s fair for you to make the final call. I just want to encourage you in this difficult situation!