Here is how i add and arrange the forms based on their Tag:

public static void AddForm(Form parentForm, Form childForm, int tag)
        {
            childForm.MdiParent = parentForm;
            childForm.Tag = tag;
            childForm.Show();
        }
public static void ArrangeChildForms(Form parentForm)
        {
            int numberOfColumns = parentForm.MdiChildren.Length / 2 + parentForm.MdiChildren.Length % 2;
            int numberOfChildForms = parentForm.MdiChildren.Length;

            int availableWidth = parentForm.ClientSize.Width - 20;
            int availableHeight = parentForm.ClientSize.Height;

            int childFormWidth = availableWidth / numberOfColumns;
            int childFormHeight = availableHeight / 2;

            Form[] sortedChildren = parentForm.MdiChildren.OrderBy(child => (int)child.Tag).ToArray();

            for (int i = 0; i < numberOfChildForms; i++)
            {
                Form child = sortedChildren[i];
                int row = i / numberOfColumns;
                int col = i % numberOfColumns;
                child.Left = col * childFormWidth;
                child.Top = row * childFormHeight;
                child.Width = childFormWidth;
                child.Height = childFormHeight;
            }
        }

Here is how i call the methods in container/parent form (called after parent form is fully loaded):

foreach (var (machine, i) in _lstMachine.Select((machine, i) => (machine, i)))
        {
            Form form = GetForm(machine.CommunicationType, machine.ID);
            AddForm(this, form, i);
        }
        ArrangeChildForms(this);

The problem is it shows the entire process of adding child forms and arranging them, but I want to hide all the child forms until they are arranged to their place. I’ve tried tinkering around the visibility of the forms, move the childForm.Show() from AddForm() to ArrangeChildForms(), use SuspendLayout() in the container but it doesn’t work either. Hopefully I can get some insights about this problem.