"briefing them" is correct and usable in written English.
You can use it when talking about providing information to people. For example: "I spent the morning briefing them about the new project."
Or "Actually, NHS funding is not my area" when you are up against politicians who have had teams briefing them.
The senators said NASA had failed to provide required reports to Congress and requested that a NASA official begin briefing them every other week about the agency's efforts.
On a Saturday late last month, the day of his inauguration, Mr. Acheampong-Tieku spent the day racing around the Bronx, greeting tribal elders and briefing them on the ceremony and news from the local Ashanti population.
That might not matter a whole lot, except that a few minutes ago the head of Nato was carefully briefing them - and the heads of HSBC, Shell and Deutsche Bank - on the situation in Ukraine.
The Pirates know they are sailing into uncharted waters but 17 of their players are full-time professionals and one has been briefing them with inside information this week.
Within five minutes, hisbah militants were rounding me up as the intelligence man who spotted me was briefing them that I had stolen some of the cigarettes from the vendors.
