If I decide to add EM or other additive to them later, would I need to let them steep more? ie if I add an acid or sweetener.
Since you have already made them, let it go for now.
You may like them as they are.
I would test them first, and then decide if you want to "tweak" them.
I use Lemon juice (yep, the bottle that looks like a little lemon ) in my fruits
I use vape wizard or apple cider vinegar in my tobaccos, chocolates, dark type juices.
I use EM to blend, add moisture, and merge the flavors any flavors.
I also use TFA Smooth (under tobacco listings) with any flavors.
Smooth has no flavor on it's own, but adds a "body" background to fruits and brings them together.
I also use Acety Pyrazine (TFA) in tobaccos and any bakery juice.
It brings out the bakery type flavor and adds a nutty flavor. Great w/RY4's
These are all "additives" and used in very small amounts, (like a drop in 3-5ml), but each does it's own thing to the PH of the juice.
You don't combo them in a juice, you pick the one that you feel will make the improvement your looking for, after deciding "it needs something"
You can add sweetner anytime, but if you use any of the others, I'd give them some time to work,
and shake'm each time you go past them.
I stay about 4 weeks ahead of myself, so all my juices have time to steep and do their thing
It's easier for me, as I've been at it for a while, and pretty much know what to add to what to suit me.
Even if it's a new recipe, I'm making a test bottle of, I add my own touches in the beginning.
At least I don't have to redo and tweak 3 or 4 times anymore.
You'll get there, but all of the ones I mentioned can help it become a "keeper" recipe.
One more hint ... when you find a juice you like and want to keep on hand, try this.
When it's down to about a ml left in the bottle ... make it again, and put it into the same bottle with what's left.
For some unexplained reason (to me) it acts as "seed" and the steep time is cut way back.
But it's just as easy to make 2 bottles of it at a time, and stash one.
When you finish the first one, make more, stash it, and use the one you had "steeping".
That way you always have one ready to go.
OK, it's bed time ... have fun