Create Matrix Table Question with Uneven Number of Statements

I think using display: none was hiding the first scale point's checkbox, but its removal was causing the second scale point's checkbox to slide over into the first scale point's position. Using visibility: hidden works to keep the structure the same. Try this:

Create a matrix question with 7 statements and 2 scale points. Allow multiple answers to make checkboxes. Add the below JS which:

• Enforces selection limit of 1 checkbox for the first scale point (unchecks previous box when another box is checked)
• Enforces selection limit of 2 checkboxes for the second scale point (no more boxes can be checked when 2 are checked - must unselect to check new boxes)
• Adds visibility: hidden on the checkboxes in the first scale point for specific rows

Qualtrics.SurveyEngine.addOnReady(function()
{
	/*Place your JavaScript here to run when the page is fully displayed*/

var qid = this.questionId;

    // Get all checkboxes for Primary and Secondary columns
    var primaryCheckboxes = document.querySelectorAll('input[id^="QR~' + qid + '"][id$="~1"]');
    var secondaryCheckboxes = document.querySelectorAll('input[id^="QR~' + qid + '"][id$="~2"]');

    // Function to update disabled state for Secondary column
    function updateSecondaryState() {
        var checkedSecondary = Array.from(secondaryCheckboxes).filter(function(c) { return c.checked; });
        if (checkedSecondary.length >= 2) {
            secondaryCheckboxes.forEach(function(cb) {
                if (!cb.checked) {
                    cb.disabled = true; // Disable unchecked boxes
                }
            });
        } else {
            secondaryCheckboxes.forEach(function(cb) {
                cb.disabled = false; // Re-enable if under limit
            });
        }
    }

    // Limit Primary to 1 selection
    primaryCheckboxes.forEach(function(cb) {
        cb.addEventListener('change', function() {
            if (cb.checked) {
                primaryCheckboxes.forEach(function(other) {
                    if (other !== cb) {
                        other.checked = false;
                    }
                });
            }
        });
    });

    // Limit Secondary to 2 selections and disable extras
    secondaryCheckboxes.forEach(function(cb) {
        cb.addEventListener('change', function() {
            updateSecondaryState();
        });
    });

// Hide Primary column checkboxes for specific statements
var rowsToHide = [4,5,6,7];
    rowsToHide.forEach(function(rowNum) {
        var checkbox = document.querySelector('input[id="QR~' + qid + '~' + rowNum + '~1"]');
        if (checkbox) {
            var tdCell = checkbox.closest('td'); // This should be the <td class="c4">
            if (tdCell) {
                tdCell.style.visibility = 'hidden';
            }
        }
    });

});