Use dimension from cloudwatch as search expression in grafana

Hi,

I am trying to create a dashboard in Grafana from cloudwatch to check subnet IPs count.
Custom metrics have been created for above request with namespace “Subnet-IP-Metric” and dimension as “Subnet IP availability” which consist of percentage of subnet IP available in particular region.

Issue is I have multiple metric name which needs to be clubbed in one.
But I have single dimension name which can be used.

I tried search expression, but there also it is asking for metric name which I can’t give. As there are multiple metrics and those metrics are dynamic. It can increase in number if new subnets gets added.
But dimension will be fixed.
I am new to Grafana. what can be the possible solution to this.

I am using Grafana UI with * v7.3.5 (11f305f88a)