OTTAWA—Capping an extraordinary exchange of demands and counter-demands, a lawyer for WE Charity’s co-founders agreed late Thursday that Craig and Marc Kielburger will appear Monday before the House of Commons ethics committee. As long as he can “intervene where necessary to provide advice to our clients,” lawyer William McDowell wrote in a letter to the committee’s chair, Conservative MP Chris Warkentin. “As you can appreciate, counsel must be permitted to protect clients’ rights in this way rather than to be relegated to a purely ornamental role,” he wrote. The brothers’ appearance has been in doubt after a fresh spat broke out between the Kielburgers and the MPs who want to grill them about the organization they founded. The brothers suggested they might not accept a summons to appear at the committee Monday unless a list of conditions were met. Those demands came after the pair first accepted the summons issued …