Speaking from experience on both sides of this situation (as bereaved parent, and as nurse assisting bereaved parents), it should be entirely the parent's choice. The checklist should be available to be sure that all the same things are offered to families, to make things equitable and consistent, but it would be inappropriate to follow it rigidly without respect to differences between families. The appropriateness depends on things being handled sensitively and respectfully towards the family. In some cases where a death is anticipated, some parents find it meaningful to take footprints and handprints themselves, or have the nurse take the prints, from their living baby, just as you would for any newborn. The nurse will be their assistant as they do these things, steadying the baby's hand or foot, getting the paper and ink, providing bathing supplies, and so forth. In other cases, it will be done after death, again, sometimes by the parents themselves, if that is what they prefer, or sometimes by a nurse. It is a best practice not to take anything away from the parents that they might want to do themselves. The nurse should fade into the background and appear only when something is needed.
With all that said, I don't think there's any evidence that if LL was taking footprints or making a memory box before the baby had died, that it was out of respect for the parent's wishes.