Same could be said for her though grabbing everything she could from the farm, writing notes and pretending she's Miss Marpke searching for things to implicate Jeremy, which relative threatened him with legal action over 3 paintings in the farm and demanded they be relinquished to them?
Grabbing everything she could

. You are getting over excited again.
The relatives did not think Sheila was capable of committing the massacre. So went to the police.
They looked for evidence after Stan Jones gave them the keys to WHF for a tidy up. Bamber was in Amsterdam buying drugs.
The relatives found the silencer. BW & Basil Cock were also in the building.