Housing benefit shortfall during UC migration

Hi.
My daughter is experiencing the above issue. For context she is disabled , a wheelchair user and receives PIP HR care and mobility. Lives in an adapted Housing Association property in Hertfordshire with her partner and 4 kids aged 3-11. Two of her children are disabled, (one in receipt of dla).
Her current issue relates to HB /discretionary housing payment.
Her query is below in her words:

‘We have arrears of £450 rent left from housing benefit due to them always paying in arrears, we also will have an additional shortfall of £50 not covered by the UC payment during our migration time - other things will be backdated but not this as it is a discretionary housing payment shortfall. We however cannot apply for the DHP until fully migrated to UC and DHP only pays for future rent not past arrears. We are being told we will have to pay the arrears ourselves. But in future we will be covered. Is this information correct? Or should this be covered eventually?’

She has just received confirmation that first UC payment will be 12 Dec . Thank you.

Thank you so much. My instinct was that it was wrong, but I didn’t have much to back that up. Much appreciated

Hello, my daughter has just given me an update on the query detailed above .
She has been turned down for DHP on the grounds that the shortfall is for service charges which cannot be covered by DHP.

The service charges (it’s a housing association property) were previously covered by HB.
She is not even sure if it is correct that the shortfall is down to service charges as UC have told her that the shortfall is caused by the rent being for 53 weeks and they will only pay 52.
And there are also the arrears accumulated when she didn’t get HB during the process of migrating to UC.
Someone did mention to her that she will get transitional protection, but she doesn’t know if that means the shortfall will be covered eventually . She is still receiving demands for payment