Operating multiple businesses under one LLC exposes all of them to shared legal and financial risk. Each serious business needs its own LLC to isolate that risk. Filing a DBA for a subsidiary business doesn't create a separate legal entity and offers no liability protection.
Chapters
If you're operating multiple businesses under one LLC, then just know that you are exposing yourself and your other businesses to unnecessary risk. Having an LLC is great because it will provide you with some personal liability protections if you operate it correctly, but operating multiple businesses under one LLC is rarely something that you should do. The reason is because if one of the businesses under the LLC gets into legal or financial trouble, then they're going to go after the LLC, which has a ton of different businesses underneath it. So now all of the businesses are at risk. So if you're serious about building these businesses, then what you should strongly consider doing is separating them into separate LLCs. Also, simply registering a DBA for the other businesses underneath the LLC will not provide you with any protection. A DBA is not a separate legal entity.