How would I give an item to a specific slot? I want to avoid /replaceitem because I want the items to stack. In the map I am making, I /replaceitem a single arrow every few seconds, but I want to have the max they can hold 2 arrows instead of 1.
If I were to do this, I would assume this creates a problem where they would just be able to rack up more than two arrows if they didn't use them before they get another. How do I get around this?
I'm not exactly sure what you mean by "if I were to do this," but if I'm understanding you correctly, use /replaceitem for the first arrow and /give for the second. The second arrow will automatically stack with the first. Then, assuming the arrows are still in the same inventory slot, the next time /replaceitem runs it will replace the stack of two arrows with a single arrow, keeping players from saving up extras.
Of course, people could rack up arrows by moving them to a different inventory slot between command runs, but then, if I understand your system, that's also possible the way you have it implemented now.
/givedoes this already. If you wanted to restrict the items to a specific slot as defined by you, then/replaceitemdoes this. Are you asking how to group together all of an item in the player's inventory into a single stack and then move it to a specific slot?