Would it be possible for Associated Partners to recruit additional researchers with own funding and join a cascading type of COFUND programme in that way?

In line with the definition of Associated partners in the MSCA Work programme 2021-2022, they cannot recruit researchers. Associated partners will not receive EU funding, however there may be arrangements in the partnership agreement between the beneficiary and the associated partners to cover specific cost categories of the programme given the co-funding, this is dealt in the partnership agreement and does not involve the EU funds.