How to switch menus without overriding the previous menu.

[cjodo]

I have this logic to focus to the next menu in a layout

vim.keymap.set('n', "<CR>", function()
  vim.api.nvim_set_current_buf(right_menu.bufnr)
end, { buffer = left_menu.bufnr })

The right menu is focused after pressing enter but the left menu items are replaced with the right menu items.

Layout mounts:

After enter is pressed:

I'm trying to keep the selected item in the left menu highlighted, while being able to select a second option in the right menu.