Hi,
after watching pic, the child can be categorized as follow: severe to moderate spasticity in four limbs, pattern of posture is hyperflexion, symmetry in pattern of posture, one side being used for fixation (L) to balance himself, tends to do small movts within the base of support.

on the basis of above observations, treatment must be based on these lines:
reduce spasticity in upper limbs to start wid the session by taking it in tone influencing pattern of external rotation, abd and retraction of shoulder. child would need mobilization of shoulder and scapula, both, in side lying position first as a preparation for this tone influencing pattern. keeping his upper limbs in this position in supine would reduce spasticity in legs and would be easy to apart his legs. once spaticity is reduced try to do big shld movements in supine lying in abduction. avoid doing activity like gripping something or grasp rather involve him in activities with open hands like hitting something.

introduce assymmetry by taking him in side sitting on right side keeping shld in TIP. introduce rotations in trunk by moving him from side sitting to prone over elbow or palms over the roll or cushion, and then get him back again in side sitting position or may be in long sitting if child can tolerate it. also introduce tunk rot in long sitting bearing weight on one arm bringing another arm diagnolly crossing the mid line.

introduce balancing exercises in prone lying and supine lying on balance board and then in sitting on ball in small amplitude to teach weight shifting on pelvis.

start using bench for him for sitting in stride sitting and sitting on one side. integrate assymmetry by keeping one foot high on small foot rest. and then try again big shld movements wid same activities as in lying and trunk rot activities using arms diagnolly by crossing the midline.

avoid using lot of standing at this point rather we can proceed to halfkneelig later on. as this will give assymetry and tip at legs together.

dont forget to keep this child moving in and out of the position during therapy rather than stucking him in one position for long times. and pay special attention to develop balancing reactions in supine, prone, and sitting.

hope this will be helpful.
thnx. regards