Keep an instance attached to ELB when autoscale is scaled to

I have a use case to keep selected instances during a zoom event in an ELB application. I know it has a connection timeout with a maximum of 1 hour, but is too short. I have Lifecycle hooks on an instance to send heartbeat, so the instance will not be removed from the ASG, but it will be removed from the ELB after an hour.

Is there a way to keep the instance attached to ELB until the heartbeat stops. Actual use case: I have a video bridging server in the Autoscaling group, so in the scale, in case I don't want users to be disconnected, instead move the instance to maintenance mode (no new calls will be scheduled) and wait until the started calls are zero and finally removed from both ASG and ELB.