DeLuca, who was a founding director at APCO Worldwide and Open Road, joins from a role as director at Teneo Blue Rubicon, which had acquired the latter agency in 2014.
Starting this month, he will sit on the agency's international advisory board and work globally throughout FHF's public affairs practices.
Snowball, who earlier in his career was comms director for the Liberal Democrats, joins in October from a role as head of public affairs at PHA Media.
He will take responsibility for FHF's public affairs team, working closely with DeLuca and the wider team in the agency's London office. He takes over from Michelle Di Leo, who moved to iNHouse Communications earlier in the year.
FHF CEO Jim Donaldson said: "We are very pleased to have secured the services of both Nick and Tim to add to our senior bench strength. We have had a very good couple of years and hiring these types of quality senior individuals will help to continue our growth trajectory into 2018 and beyond."
DeLuca and Snowball are the latest in a series of hires at the agency. In April, FHF added senior director and partner Michael Hartt from Burson-Marsteller in a cross-practice role, and promoted Steph Bailey to the role of MD of its corporate practice in London.