Qualtrics.SurveyEngine.addOnReady(function () {
    let quest = this;
    let boxes = quest.questionContainer.querySelectorAll(".AnswerContainer"),
        add_button = quest.questionContainer.querySelector("#addbutton"),
        remove_button = quest.questionContainer.querySelector("#removebutton"),
        tracker = 1,
        all_choices = quest.getChoices();

    boxes.forEach((box) => box.hide());
    boxes
    add_button.onclick = function () {
        if (tracker < boxes.length) {
            tracker++;
            boxes�tracker - 1].show();
        } else {
            alert("Max Boxes");
        }
    };

    remove_button.onclick = function () {
        if (tracker <= 1) {
            alert("Min Boxes");
            return false;
        }
        let clear_choices = �];
        all_choices.forEach((item) => {
            if (quest.getChoiceAnswerValue(item) == tracker) clear_choices.push(item);
        });
        clear_choices.forEach((ch) => {
            quest.setChoiceAnswerValue(ch, tracker, 0);
        });
        tracker--;
        boxesttracker].hide();
    };
});

This won't work for PGR, but if you can move to Matrix Single answer, drag and drop, the code above will do the trick.

Thanks so much for the answer! and it might definitely work using the matrix single answer question type instead.
I tested the code but the problem remains that when I remove a group, the objects that I have put it that box still appears when a group is added again. I need the objects to be thrown back into the list of objects when a group is removed. Am I missing anything that I need to add to the code?
This is how it looks with the code you suggested + my html.
https://samgu.eu.qualtrics.com/jfe/form/SV_8iHuwbj8zS9HNRQ
Thanks again!

Create a new question and copy the JS there.
The problem is that you've probably made changes to your scale points, hence the numbering is not 1,2,3... but is something more like 4,5,6...
Demo.

Oh alright, yeah that works great! Thanks so much for the help.
One problem still remains though: Currently, the item that is thrown back ends up at the end of the list. I need it to go back to its initial place (i.e. Statement 1 goes at the top of the list and not at the end of the list). Would that be possible to solve?
Also, if it's not too much to ask for, I wonder if you would be kind to specify code to keep the items in three-ish columns. I noticed now that a list of 38 items is not that easy to get an overview of when the are all listed in a long list.

The first one is too much work. May get around to it sometime.
For the second one, check out my earlier comments, I think I answered in Dec/Jan. It doesn't keep them in columns, but keeps the boxes in view while scrolling down.

Alright, I understand. Thanks so much for the help, really appreciate it!