Adopting a community-led approach does require some discussion with funding partners, but it is often very doable.
For donors who typically support top-down approaches, one useful strategy is to develop small pilot projects that are community-led, possibly as an accompaniment to work that you are already doing under a grant from the donor. Quite often, donors are willing to scale up an option that has data (even simply in a case study format) to support it.
Another option is to seek funding, even a small amount, from a private donor who likes to support more community-led approaches.
Alternately, some international NGOs have more flexible, long-term pots of funding available in parallel to their traditional funding arrangements. Usually these funds are intended for activities such as sponsoring children, but in some cases they may be released for other purposes within an appropriate partnership.
Finally, you could invite community groups—such as youth groups or women's groups—to develop their own initiatives at little or no cost, as a complement to the more typical top-down work being done in their community.
Over the longer term, it is useful to educate donors who are concerned about achieving positive results on behalf of children. Persistence and the discussion of positive results can go a long way towards helping them welcome a community-led approach.