read the obit of his son (which was easily findable by plugging 'Joseph Marsdem' into search engine on MNB - in Manchester mid 1850s - appears to come to Douglas mid 1860's (not in the May 1861 list of Douglas licensees) - def in 1881 census (age 66) and 1871 index age 56 (I presume you looked for Joseph on FHSoc index) and since bur Bra 18880722 aged 74 (+ wife Louisa bur 1890) will not be found on other IoM census- however if your Marsden was born 1825 then for Joseph to be a father suggests he was exceptionally precocious - Steam Packet shares in those days were a safe investment.
If your Ann is indeed related then possible the dau of the father of the Douglas Joseph (or a bro thereof)