According to Official Guinness Records,
The most people performing aerial silks is 30 and was achieved by Private Drama, on behalf of MACE Group (both UK), at Old Billingsgate, in London, UK, on 24 June 2015. The record attempt was arranged for MACE Group’s 25th anniversary as part of their mission to promote the spirit of adventure.
For a complete list of 2015 records, please visit 2015 Guinness Records in United Kingdom.