I work with my siblings, one slightly older and one slightly younger. It definitely makes for an interesting dynamic, although since running the shop online is completely my responsibility I have perhaps an unusually large amount of say in how things go – prices, for example, are entirely figured out by me and while they might suggest raising or lowering something, in the end I'm the one who crunches the numbers and decides what goes up.
It's very nice to have help on designs, though, and I never feel like I'm going in alone, even if we sometimes disagree on things. I don't think having help would ruin your shop identity at all. The patterns are still yours, aren't they? The shop is yours. By outsourcing and getting help that will make you more productive, you're just demonstrating good business sense that will probably help you in the long run.