DLA- adding mobility onto son's claim

[1995SENNDMUM]

DS turns 5 in november, so just been onto them to chase a COC form.
What I'm not too sure on is exactly what to write for mobility.

He's non verbal, very severe receptive language delay, think 18 months level so has just start responding to very short instructions, but we don't have a learning disability diagnosis or IQ test results (might be looking at being referred back to paeds when he starts school for an LD assessment but would probably be more moderate than severe range from what's been said previously by LD sleep nurse), so reasonable sure he can't fit under SMI, and i don't know if VUW is worth trying for at this point.
Can I simply write "no danger awareness, needs constant supervision outdoors and regularly needs his disability buggy due to overwhelm" to cover low rate mobility, is it really as simple as that or will they want more detail?
Of course I'll reiterate all his care needs and have more recent evidence they can have for those so I'm not worried he'll lose his care rate.

You should give more detail. Explain exactly what happens and what support DS needs.

BTW, there are other ways of meeting the “an incomplete physical development of the brain“ or “arrested development which results in severe impairment of intelligence and social functioning“ criteria for SMI other than a LD diagnosis. And it is possible to met the severe impairment of intelligence even with an IQ over 55 if the person can’t apply their intelligence in the real world.

Thank you for your help. He has an ASD diagnosis, EHCP and starts a GLD special school for reception in September, but we don't currently have high-rate care, only middle-rate. His EP report listed his development as 9-12 months in language and the same for social development but otherwise there's no more numbers there if that makes sense, just very detail descriptions of his needs so i wasn't sure it would be enough without that IQ testing or LD diagnosis.

We can get him to walk more than 50ms when he's well regulated with constant supervision so i don't think we can try virtually unable to walk route?
His sleep issues are 6 nights a week on average, maybe 3 nights a month he doesn't need supervision/support from us, so i'm not certain he'll get changed to high rate care or not this time to meet the HRC criteria for that part of SMI.
Then we don't officially have restraint plans currently in nursery, so i wasn't sure about ticking that part of either.

Obviously the other parts of the criteria still need to be met, including HRC (which it sounds like DS should be eligible for), but an ASD diagnosis can count as arrested development. A LD diagnosis isn’t required. And depending on the other evidence, it is possible to demonstrate the tests are met without IQ testing too. A formal restraint plan isn’t essential if you can prove restraint is actually needed/used.

On VUW, if DS can walk more than 50m the majority of the time, he wouldn’t be eligible. When looking at whether DS can walk think about the manner he walks, the time it takes, any interruptions frequent enough to significantly limit DS’s ability to make progress.

I meant to add, if you haven’t already looked at them, the SMI and VUW criteria flowcharts are in this document. Also Contact’s leaflet is helpful.

Thank you again for your help, I just really wasn't confident if the HRC was even possible as at the renewal they said night needs were enough but I've got a lot more now, I'll have a look through the flowchart and answer the form as if HRM could be possible but I'll happily accept LRM if its a no.