'Purge'? Are you SERIOUS? It does indeed emit from orifices after death, 3 - 5 days later! There is n o way that blood can defy gravity as you describe. Given that 'purge' is the result of purification, the idea that this happens a few hours after death is just silly. I thought you had studied this stuff? Blood is leaving from Sheila's mouth but swapping blood for surge still leaves you with the FACT that liquid cannot defy the laws of gravity and for her head to be propped up, it would have ran DOWN her face, not up.
Decomposition is not a one size fits all, many factors influence it, and you do not know what effect, if any, SC's pharmacology had on it.
Martyn Ismail is clear that upon infliction of the second gsw SC's head fell back against the bedside cabinet. At circa 7.30 pm A/PS Woodcock also observed SC's head propped up against the bedside cabinet. At circa 10.30 pm soc images show her head flat to the floor. What happened between 7.30 pm to 10.30 pm? It certainly wasn't JB who staged soc as he was outside with EP.
MI's evidence explains why those first at soc who also left early report seeing one gsw ie when her head was propped up against the bedside cabinet it concealed the upper gsw. Those who arrived and/or left later report seeing two gsw's because when she was pulled by her feet and her head fell flat to the floor the upper gsw was revealed.
It also explains that the large blood stain on the carpet under the bible in the soc image doesn't correspond with the blood staining under SC's armpit. Whereas it would if her head was propped up against the bedside cabinet. Same for the blood staining on the bible ie the large stain should correspond with the large stain on the carpet which no doubt it did before it was moved around by EP.