What would you suggest the best thing is to do with an incomplete set of volumes, sell them individually or as an incomplete set?

The spine has 4 gilt emblems, would this be indicative of the number of volumes in the complete set?

Butler's Lives of the Fathers, Martyrs and Other Saints Volumes II, III, IV
undated circa 1920/30
400+pp per volume
Virtue & Co. LD.
numerous colour plates - all present
olive green & black boards with gilt title and design to front and spine
some bumping to extremities otherwise condition is very good.
______________________________________________

Another title to eBay or not to eBay:

The Crime of the "Liza Jane"
Fergus Hume
Ward, Lock & Bowden Limited
1895
2 full page illustrations - both present, frontispiece loose.
Green cloth boards with dramatic design to front - boat on sea under a moonlit sky, hand clutching dagger and twisting snake around gilt title. Hand, snake and dagger motif to spine.
Some bumping to corners and head and tail of spine. A few spots of foxing.

Thanks, people.