Hi -- Any insurance policies left by a deceased person belong primarily to the estate of the person who has deceased, unless they were specifically intended for the direct benefit or actually named another person as the beneficiary.
Therefore unless these insurance policies have specifically named the eldest child......then they have no right whatsoever to the proceeds of your Mother's policies, any funds from them should first go towards her funeral arrangements.
I take your post to mean that the insurance policies will cover the bulk of the funeral costs, but that you all may be required to add a further £40 (ish) to ensure the anticipated shortfall has been fully covered.
Does the eldest child expect to keep all the policy proceeds to theirself and make all the other family members contribute the full costs to your Mums funeral ?...........Disgusting if so.!