The appointments follows a Labour reshuffle which is now into its fourth day and has seen Stalybridge and Hyde MP Jonathan Reynolds stand down from the frontbench, citing differences of opinion with the leadership.
He became the third front bencher to resign today after Mr Corbyn sacked two "disloyal" senior figures and promoted a Trident opponent in his so-called "revenge reshuffle".
Kevan Jones claimed his former boss Maria Eagle, a supporter of Trident, had been moved from the defence brief against her will despite briefings that taking on the shadow culture secretary role was her "dream".
But he added Europe spokesman Pat McFadden to the casualty list alongside shadow culture secretary Michael Dugher.
An ally of Mr Corbyn accused centrist MPs of conducting a "deliberate" and "co-ordinated" effort to undermine the leadership by "lying" about the reasons for Mr McFadden's sacking.
In what was seen as a compromise with Labour's more moderate members, however, the party's shadow foreign minister Hilary Benn, who had been tipped to be ousted after openly opposing Corbyn a year ago over military action in Syria, kept his job.
Labour announced that former junior education spokeswoman Pat Glass would replace Europe shadow secretary Pat McFadden, while Emily Thornberry would replace Maria Eagle as defense spokeswoman.
He denied he had been "muzzled" by Corbyn, after reportedly agreeing not to publicly criticise the leader's policy positions.
McDonnell said Mr Corbyn was trying to "hold everyone together but be very clear about our direction of travel in terms of policy".
He said the reshuffle had been an "adjustment" and took so long because so many Labour members wanted to talk things through. The CSU conference visit forms parts of these continuing talks - with politicians on both the left and right in Germany showing some support for his more controversial proposals, especially a bid to limit access to state welfare for European Union migrants in a new country.
He defended the length of the reshuffle, saying his "great failing in life" is to "listen to everybody at whatever great length they wish to speak to me".
Mr Benn was the Hashim Amla - the South African captain who batted obdurately for two days - of the shadow cabinet, digging in and refusing to budge.
All the focus was on whether Corbyn would sack Benn, with rumours swirling that if he was axed, other centrists would quit the shadow cabinet en masse.
Labour grandee Lord Mandelson said the reshuffle " takes Labour even further away from any prospect of winning a general election" by focusing on moving to a policy of unilateral disarmament. However, if he disagrees with Corbyn, he won't be able to express those views from the Labour front bench in the House of Commons, the party's finance spokesman, John McDonnell, told BBC Radio 4 on Wednesday.
Describing the decisions as a "mistake", Mr Corbyn then told the PM about a couple in York whose home was flooded, causing some Tory MPs to laugh.
"The question is what on earth is the member of Leeds Central and others doing in this Labour party government".
