I've been reading the coresponding ship list to Hero 2 (march 24,1887 Trodhiem-Christiansund -Aalesund- Hull)Especialy the one that lists it leavesGlasgow. Departure was March 30,1887 Then arrived at Liverpool March31, 1887 to Boston.Then back to Halifax April 10th.
I was refering to the ship list on this program. Norway heritage.com Under Allan Line Ship S/S Siberian.The coresponding ship would be Hero 2 from Trodhiem Norway on March 23,1887.
The remarks posted for that particular voyage of the SS Siberian does not say whether the ship stopped first in Halifax or Boston.
Since it lists Halifax arrival as 10 April 1887 you could look for Boston arrivals near that date to make your final determination of which stop was first. Boston ship manifests would be available to you through the US National Archives - and/or possibly on microfilm copies through the LDS Family History Library collection.