No, that info didn't work out with any solutions either.

The sinister side definitely appear to be those of a STACPOOLE daughter (Irish) - still looking around fot the dexter (male) side of those 'arms of a marriage'.

Any children of that marriage would not have been able to use those arms, only the ones on the dexter side of the shield as the wife was not an heraldic heiress in her own right, or the arms would have been quartered and her children would then have been entitled to bear quartered arms.

** Viscount Richard de Stacpoole, was given the Order of St Gregory, and was created Marquis by Pope Leo X11 1828 for services rendered to the church... **
It would be an interesting aside to follow this one up as it raises more questions. It obviously wasn't a French marquisate he was given as all those sorts of things went out with the French Revolution in the 1790s and couldn't have been a marquisate of the Holy Roman Empire because that ceased to exist in 1806. I wasn't aware that popes had the power to create marquisates anywhere, not even in Italy. Where did that info come from?