2.6 DHF/Rekons extremely light rider \(105lbs\) on 160mm travel MTB \(Pivot Mach 6\)

Just mounted these brand new tires on DT Swiss 1700 30mm \(internal\) for my wife \(coming from 2.3 Highroller IIs which we ran at 21f / 24r\) and we are struggling to reduce the amount of BOUNCE she is experiencing over every root / rock / feature. We started at 18f / 20r and have dropped to 15f / 16r and the extreme bouncing is still apparent. I suspect that either going up into the mid twenties \(to harden them back up\) or even lower to the low teens might be the cure - but wondering if anyone else has any experience / input how to tune these relatively high volume tires to a very light rider. As for her riding style / level, she rides the intermediate group locally. Thanks in advance :\)

PS. Reason for swapping out was better roll-over, slightly better pedaling ease etc. of which they are an improvement.