Welcome to Just Answer and thanks for your question. I am assuming your Johan(n) Schusler was the one in the convalescent home in Pegwell in 1901. If that is the one, he is also in the 1891 census. His death is registered in the 4th quarter of 1901 in Hackney, London. His full name was John (i.e. Johann in German) Matthew Schusler.
1891 CENSUS -XXXXX Hackney, South Hackney, London
- John M. Schusler Head 47 N b b abt 1844 Cabinet maker b Germany
- Madeline Schusler wife 44 F b abt 1847 in Germany
- Frances Schusler Dau 18 F b abt 1873 Tailoress, b Bethnal Green, London
- Annie Schusler Dau 15 F b abt 1876 Tailoress, b Hackney, London
- Louisa Schusler Dau 9 F b abt 1882 Scholar, b Hackney, London
- Lilley[sic] Schusler Dau 5 F b abt 1886 Scholar b Hackney, London
I don't see Johann in the 1881 census, but his wife and daughters are here:
1881 Census -XXXXX Hackney, South Hackney, London
- Madeline Schusler Married 32 F b abt 1849 b foreign (France)
- Mary Schusler Dau 9 F b abt b abt 1872 b Whitechapel, Middlesex
- Frances Schusler Dau 7 F b abt 1874 b Bethnal Green, Middlesex
- Anne Schusler Dau 4 F b abt 1877 b Hackney, Middlesex
I did not find them in the 1871 census, although they may have been in England since their eldest daughter was born in Middlesex/Londonshire in 1872.
Without knowing where they came from in Germany and finding the parents, there really isn't a good way to tell if he had siblings or if others came with him and Madeline. You may want to check published passenger lists for entries into England around 1870-1872 to see if you can find them. Some lists included home addresses while others just had the country they were coming from. There may also be emigration records from Germany but those aren't online either.
If this is the same family, daughter Frances Paulina married Edwin James Gooch in 1896 and daughter Annie Catherine married Athelstane John Kent in 1900.
1911 Census -XXXXX Hackney, South Hackney, London
- Madeline Schusler Widow 64 F b abt 1847 Germany
- Louisa Schusler Dau 28 F b abt 1883 Trouser maker b Hackney, London
- Lily Schusler Dau 25 F b abt 1886 waitress b Hackney, London
- Edwin Gooch Grandson 17 M b abt 1894 Cabinet maker b Hackney, London
- Joseph Trost Nurse Child 6 M b abt 1905 St. Luke's, London