Hi Stephen,
So glad you've come onto the member's forum. You don't say how these people are related to you, and I'm going to assume that you have researched the Schmal from your father, going back. Perhaps these are siblings of a direct ancestor, if I were to guess.
Some of these suggestions you may have already tried, but you never know if something I say triggers you to look AGAIN at something. I've had that happen, myself.
Again assuming you have the direct ancestors already fully researched, which probably is what led you to the home town. I sense you're already aware of how VARIABLE names can be, so as you look at ship manifests for that time, forget looking at names. If you know what GERMAN names they may have used, you could try just the first names. But instead, try searching manifests just with dates of possible births for the three of them. And, unless you're POSITIVE of what port they arrived in, look at various ports. These earlier ship manifests are so sparse, that sometimes all you really can do is guess...
If these three came to America around 1848, they should show up somewhere on an 1850 census. Likely at least Mathilde and Abraham are probably together, maybe with Esther, maybe not. And all three of them could have TOTALLY changed their names, too!
If you haven't done so already, I'd also suggest DNA. As I researched my paternal g-grandmother, although I was able to find her parents, in Poland, and a sister and her family, in Poland, I never had ANY indication that the sister and her family had come to America. UNTIL a DNA match of a g-granddaughter of that sister contacted me, Then two MORE DNA match descendants of that same sister contacted me, one of which is in her 90s and could provide me with FIRST HAND information! It opened up a HUGE story that I never would have been able to put together if it hadn't been from those accounts.
Do NOT forget that we have the "Ask a Genealogist" call each month, which can be VERY helpful, and more in-depth than you would expect. The link to sign up for September's call is https://casdgs.org/event-6247332?CalendarViewType=1&SelectedDate=8/31/2025, and I suggest if you DO sign up for it, go ahead and reach out to Anne ahead of time with your question.
One more thing; Be sure that, as you do your research on each of these people, be sure to create a research plan and log. I spent years trying to find a system that would keep my genealogy research organized, and today I can walk away from a person I'm researching and be able to tell where I left off, rather than have to repeat myself (over and over and over). I'm happy to share my template with you if you'd like.
Good luck and I hope some of this helps. And do NOT discount going to one (or a few) of the Ask a Genealogist sessions. There often are very few people, so it's very likely your questions will be addressed. And you can never have TOO many people helping!
Margie