Our State does not require that we enroll but this will be our first year and feel we need a little more of a guiding hand at least for the first year. Right now we feel like we're getting off a large ship and into a tiny dinghy (the best metaphor I can use for going from a parochial school to HS). We are homeschooling because we have been left with no other choice although my husband and I want to do it and our children want to do it too. The parochial school systems here in our city has failed our children from many angles including using common core - ughh. they're going into 3rd & 4th grade. I will check out Angelicum!
There are a LOT of choices other than Seton & Kolbe. Mother of Divine Grace is roughly as "classical" in outlook as Kolbe, IMO. Catholic Heritage Curricula isn't classical and doesn't offer enrollment, but would have more Catholic materials (than Memoria Press) if you are picking & choosing. Their Behold & See Science is a favorite for some & you could combine your two kids into one of the books.
If you really want hand-holding, I suggest St Thomas Aquinas Academy (STAA). They try to be classical in flavor. They also offer academic placement help and personalize the program to your kid or your family. You can call their people for a free 30 minute question & answer session. If you do this, I recommend checking out their website beforehand so you know what questions to ask. I know a couple families using this option. One calls them a lot for encouragement & questions. It will not be a one-size fits all approach. They'll work with you so that both your kids can do similar topics & may even use the same books for history or science. I believe each of your kids will have to do some testing so they can be appropriately placed in math & language arts materials.
I think Seton really pushes doing a LOT of workbook/seatwork without much flexibility & leads to burnout for the kids. Kolbe is very rigorous in the upper grades. I don't know how enrollment at the lower grades is, but I think they are more flexible than Seton.
Best of luck in your homeschooling journey. I think you'll find that after a little while, you might feel comfortable enough to do this without as much handholding.