Right to Reside with no requiremnt to meet outgoings

We are advising an Executor of an Estate which consists of a half share in a property which was held as Tenants In Common and subject to a mortgage and about £10,000.00 in cash.
The will provides that the co-owner has a right to reside in the deceased’s half share “free of charge” but the Will makes no provision with regards to the payment of outgoings such as insurance, council tax etc.
The Will provides that the Residue and the half share of the property subject to the right to reside pass to the deceased’s minor children upon the age of 18 and death of the co-owner. The children reside elsewhere from the co-owner and there is some animosity with the children’s guardian and the co-owner.
The creditors of the deceased exceed the cash in the Residue.
The co-owner is subject to their covenant with the mortgage company to pay the mortgage payments but what is the Executors position in relation to the Residue , are they entitled to retain the Residue to meet possible future liabilities in respect of the property in the event that the co-owner were to fail to do so, or is the Residue available to meet the creditors and if so to what extent as all are ordinary creditors? Are they to be paid pro-rota to the Residue , but the Estate is not actually insolvent as there is the capital in the undivided half share albeit that it is not available at this stage.

Could the Executor refuse to pay the Creditors on the basis that they need to retain the Residue to meet any future liability that may be incurred in respect of the property or use the Residue to pay the creditors proportionately in full and final settlement and if funds are needed in the future then funds will need to be found from a third party ?