Multi-manager stalwarts Gary Potter and Robert Burdett will assume management of the F&C fund of funds range following the departure of Dean Cheeseman.
Current head of multi-manager Cheeseman and co-manager Oliver Sonnbichler have agreed to leave the firm by mutual consent.
Meanwhile, Paul Carne and analyst Catherine Sauer are to join Thames River by the end of the year, with Carne heading up the Lifestyle range.
Burdett and Potter, whose Thames River boutique was acquired by F&C earlier this year, will see four of F&C's MM funds merged with equivalent funds in their range, subject to shareholder and regulatory approval.
F&C's Multi Manager Cautious, Distribution, and Balanced Managed funds will unite with Thames River's similarly-named funds. F&C Multi Manager Growth will merge with Thames River Equity Managed fund.
The merger will result in Thames River Multi-Capital becoming one of the largest players in UK retail multi-management by AUM, the group says.
Burdett says he is not likely to make major changes to holdings before the funds themselves merge, expected by year's end.
Meanwhile, F&C's head of corporate affairs Jason Hollands said he expects about a dozen redundancies among the 1,100 combined staff, but asset management teams will be kept largely intact.
Retrenchment will occur mainly among distribution and infrastructure units, he says. "You will see very little retrenchment on the investment management side."
"The attractive part of the deal is there is very little overlap. What Thames River does is mostly absolute return, whereas F&C is more long-only institutional. Cost savings is not a driver of the M&A."
'Right thing to do'
£69m spent on upgrades
European fintech market 'underserved'