на полях(какого-либо мероприятия – President Barack Obama and Russia's President Vladimir Putin met Friday on the sidelines of D-Day anniversary events in France. Ин.яз)
в кулуарах(met on the sidelines of the summit – встретились в кулуарах саммита – The president of Statoil in Russia, Jan Helge Skogen, told The Moscow Times on the sidelines of the second Norwegian-Russian Business Forum on Thursday that the company was "trying to communicate a sense of urgency" to the talks.TMT Alexander Demidov)
в рамках(As a result, the commissions were able to organize several joint interregional events, mainly on the sidelines of relevant global events – Это дало возможность комиссиям организовать ряд совместных межрегиональных мероприятий, главным образом в рамках соответствующих глобальных мероприятий Taras)
на задворках истории(1) "This election is too important to sit on the sidelines of history," said Mrs Clinton. 2) We have never been willing to stand on the sidelines of history. 3) Phil Ochs unjustly remains on the sidelines of history. Alex Krayevsky)