If you look at the SP Death Search parameters, there are three Last Name Fields to wotk with.
1 Surname [Any Surname by which the person has been known]
2 Other Surnames [by which the person has been known]
3 Mother's Maiden Surname.
Uou have to play about, from simply using any Surname in (1) to using all three.
Great fun making aure you have tried all combinations, further enhanced and/or restricted by the offered Variants such as
Exact Surname Surname Variants Soundex etc.
At times, this is where the old adage "Less is More" may be applicable, on the other hand where frequent names are involved such as Smith, the additional fields can help reduce or hit target first time.
Added to those are the approx) Year of Birth and/or (apptox) Age at Death.