The phrase "have since requested" is correct and usable in written English.
It can be used to indicate that a request was made at some point after a previous event or action.
Example: "After the meeting, we have since requested additional information from the team."
Alternatives: "have subsequently asked" or "have requested since then."
He said North Korea had since requested a further round of negotiations, which Haicheng Xiyang had refused.
He first fled to Cameroon but has since requested refuge in Benin, news reports said Friday.
Mrs. Arafat has since requested that the French authorities open a murder inquiry, and on Sunday, Mahmoud Abbas, the Palestinian Authority president and Mr. Arafat's successor, said Russian experts would also be helping with the investigation.
Mr Snowden - who was also a contractor for the National Security Agency NSAA) - has since requested asylum in Ecuador.
Tan has since requested that Yale-NUS not show the film while she appeals the ban, hoping to reverse it.
"Donald Trump: The 'Apprentice' is a television smash!" TIME has since requested Trump stop displaying the fake cover.
Porsha -- who was reportedly "completely blindsided" by the filing -- has since requested alimony and asked that she be able to stay in their matrimonial home.
Holder has maintained he was unaware of Fast and Furious until months after Agent Brian Terry's death last December and that he has since requested a Justice Department inspector general's investigation and ordered his employees never to open similar operations that include illegal gun- walking".
The Government has since requested UNICEF to review and update the national communication strategy for pandemic and avian influenza, a process which is being finalised.
Although my presence has since been requested at the table of many languages, and numerous people have invited me to sit beside them, I wish for no one else to have to do as I did, hacking at my own grave with a pick, in the hope that it was not yet ready for me.
