The co-chair of the fringe, pro-Corbyn Jewish Voice For Labour group has agreed to speak at a leftwing meeting in a church hall - on the evening of Yom Kippur.
Jenny Manson - who has repeatedly tried to stress JVL's authentic Jewish credentials - will appear alongside Weyman Bennett, a member of the Socialist Workers Party's central committee at the October 8 meeting on the rise of the far-right.
The Kol Nidre service in synagogue ahead of sunset also takes place on October 8 this year and leads into the start of the holiest day of the year in the Jewish calendar.
Ms Manson, who last year told the JC she had been hurt by people who question her Jewishness, is one of five speakers listed to take part at the West London Stand Up To Racism event.
It takes place at St Mary's Church Hall in South Ealing.
The evening is entitled Resisting the Rise of the Racists and Fascists - and is scheduled to include debate about antisemitism.
The Stand Up To Racism organisation has long been associated with the far-left Trotskyist SWP through the main speaker at the Yom Kippur clashing event - Mr Bennett.
Three years ago Mr Bennett was at the centre of claims he was involved in the cover up of a sexual assault of young SWP member.
AS one of JVL's leading figures, Ms Manson has been at the centre of attempts to deny a rise of antisemtism in Labour under Jeremy Corbyn.
The former Barnet Labour councillor and tax inspector has previously spoken of claims of anti-Jewish racism being made to "drown out other issues”.
At last week's JVL fringe events at the Labour conference, speakers urged Jewish Labour members to join the organisation - stressing that only those who were Jewish could vote on issues arising.
JVL offer a different membership scheme for those supporters who are not Jews.
Among those to attend the JVL fringe meeting last Sunday was Liberal Judaism Rabbi Danny Rich, who is considering standing for Labour in Finchley and Golders Green at the next election.
Yom Kippur, or the Day of Atonement, will see even the most unobservant Jews attend services in their local synagogue during the 25-hour fast.
According to their mission statement, JVL announced they were a group of "progressive Labour Jews" who "take inspiration from the long history of Jewish involvement in the socialist and trade-union movements."
They added: "We oppose attempts to widen the definition of antisemitism beyond its meaning of hostility towards or discrimination against Jews as Jews."
Ms Manson once told the JC: “We don’t call the Board of Deputies or the JLC, not proper Jews.
"We might disagree with them but we don’t personalise it and we certainly don’t question people’s Jewishness. In fact I think it is a strange kind of antisemitism to do that."
On Thursday, Jewish Labour Movement chair Mike Katz told the JC: “Whilst the overwhelming majority of Jews in Britain will be turning up to synagogue for the one evening when even the most unobservant will decide to be with the Community for the most solemn moment of the year, we wish Jenny a good fast for her speaking engagement.”
Last year, an event where Jewish speakers were due to question Labour antisemitism and debate "smears" against Jeremy Corbyn was rescheduled from Kol Nidre. The speakers included JVL's Jay Blackwood.
