The £773m Gilt and Fixed Interest Income fund will see Riddell taking over from Leaviss as lead manager, who will deputise for him.
UK Inflation Linked Corporate Bond, previous co-managed by Lord and Leaviss will now see the former take the lead manager position with the latter as his deputy on the £837m portfolio.
The pair also co-ran M&G's £98m European Inflation Linked Corporate Bond fund, which will now be lead managed by Leaviss, with Lord shifting into the deputy manager.
Leaviss, who heads up the retail fixed interest team, said a heightened demand for new and existing products had seen the team grow from eight to 18 members since 2009.
"With the addition of extra resource and experience to the team it is now appropriate to make adjustments to fund responsibilities. We believe these changes will allow the team to become even more focussed on asset classes than ever before, enabling fund managers to play to their strengths."
