With a managed portfolio service, the manager should find it very easy to inform advisers and investors of areas that might prove to be concerning.
It is my belief that this should be provided as an integral part of the offering - you should not have to request it.
Providing a full list of holdings does not help you if that list comprises only a breakdown of the underlying funds, and does not cover any potentially contentious companies held within those funds.
Clients are smart and deserve to know where their money is invested, so the message to fund managers is clear: if you claim to be helping clients invest in companies contributing to a better world, be proud of where you invest and the processes that you follow to select investments; and be prepared to share that process with clients.
As complicated as all this might sound, greenwash is actually very easy to avoid.
You need to be completely transparent and honest; do not making claims that are likely to confuse or mislead; provide investors and their advisers with complete clarity; and trust them to make decisions that align with their best interests.
Problem solved.