How to correctly assign values to mixed elements in FEniCS-X?

Actually this is a follow-up question of the post Solve the nonlinear coupled-field problem with FEniCSX - FEniCS Project. I am not sure if I illustrated my question clearly, and I would like to restate my question:

We have one mixed element mixed_el containing two simple elements v_el and s_el. I want to assign values 0-11 to function u0 corresponding to the element v_el, and values 0-5 to the function v0 corresponding to the element s_el. So how can I realize it?

Thanks!