Thank you for the message.HEMMINGS (& HEMMING) is a long established and quite common Worcestershire name (so is HARTLAND) and I can't see how it could be a variation of the YEOMANS name.So that family of yours must be using the two names as alternatives.
In my NEW family one of them married (c.1700) a CALLOW who with her sister 'inherited' their father's land (strips in fields?).One of her sons was married under the surname Callow although otherwise he is recorded as a NEW.However one of his daughters married a CRUMP and every generation since has carried CALLOW as a middle name up to the present day!Although the original connection was long forgotten (until recent research).
I thank it was fairly common in medieval times and later that where land passed through the female line her name could be adopted.It made 'ownership' claims easier.Tenantcies were also inherited.In fact of course all land was held as tenants of the King on various levels.(I was rather surprised to find the strip system still operating today in Hampton near Evesham.)
It would be interesting to find a YEOMANS connection in yuour HEMMINGS line further back in time.