Case sensitive body parameter for backend acls

Hi

I am working on a config using haprixy 2.2 where backends are selected using a map table and an http body parameter value. As per the documentation, the body parameter name is case sensitive so it only works for one scenario. Any change in the case of parameter name goes to default backend which is not intended. I also tried adding multiple acl rules for some known variations but only the first rule is executed and rest are ignored. Is it possible to make a case insensitive match or make multiple rules work?. Below are the example rules from my frontend

use_backend %[req.body_param(param_a),map(/data/backends.map)]
use_backend %[req.body_param(Param_a),map(/data/backends.map)]
use_backend %[req.body_param(Param_A),map(/data/backends.map)]
use_backend %[req.body_param(PARAM_A),map(/data/backends.map)]

I am fairly new to haproxy so really appreciate assistance on this

Thanks