How to deal with hardcoded requests of a webapp when using path-based location blocks?

I am trying to create a reverse proxy route using nginx-proxy and docker for OpenTripPlanner (OTP) version 1.5.0 and 2.2.0 on the same machine.

If I have a simple location block like:

location /otp2 {
        proxy_pass http://127.0.0.1:8081;
    }

The majority of calls OTP makes gets passed on to the upstream server, however the OTP web-app also has some hardcoded calls to http://host/otp and http://host/images (not http://host/otp2/otp and http://host/otp2/images). As they don't match an nginx location block, they fail to resolve.

How can I ensure these calls get routed to the upstream server as well?

What I've tried

Regex + rewrite

After a lot of fiddling around I settled on:

location ~^/(otp2|otp|images) {          
        rewrite ^(/otp2)$ $1/ permanent;
        rewrite ^/(otp2)(.*) $2 break;
        rewrite ^/(otp)(.*) /$1$2 break;
        rewrite ^/(images)(.*) $1$2 break;                                                                                                                                                                           
        proxy_pass http://127.0.0.1:8081;
    }

This works, but this prevents me from running OTP version 1.5.0 next to it, as that binary also requests http://host/otp and http://host/images.

Additionally, every other web-app I would run on that host that would have a route to /images would probably be picked up by that location block.

Subdomain

I cannot make changes to the DNS, so (I assume) I can only do path-based location blocks, and not subdomains like otp2.host.com and otp1.host.com.

Separate location blocks

Per suggestion of one of the answerers I tried separate location blocks:

location /otp2 {
    proxy_pass http://127.0.0.1:8081/;
}

location /otp2/otp {
    proxy_pass http://127.0.0.1:8081/otp/;
}

location /otp2/images {
    proxy_pass http://127.0.0.1:8081/images/;
}

This partially works, but leaves a few unhandled OTP requests which breaks the application (the host of the form sub1.sub2.company.country is obfuscated in below screenshot):

Lets use separate location block to handle the specific hardcoded requests from OTP 1.5.0 and 2.2.0, try this config:

server {
    listen 80;
    server_name your_host_name;

    # For OTP 1.5.0
    location /otp1 {
        proxy_pass http://127.0.0.1:8080;
    }

    location /otp1/otp {
        proxy_pass http://127.0.0.1:8080/otp;
    }

    location /otp1/images {
        proxy_pass http://127.0.0.1:8080/images;
    }

    # For OTP 2.2.0
    location /otp2 {
        proxy_pass http://127.0.0.1:8081;
    }

    location /otp2/otp {
        proxy_pass http://127.0.0.1:8081/otp;
    }

    location /otp2/images {
        proxy_pass http://127.0.0.1:8081/images;
    }

    # Additional web-apps with /images path
    location /other-web-app/images {
        proxy_pass http://127.0.0.1:8082/images;
    }

    # Handle remaining OTP v2 requests
    location /otp {
        proxy_pass http://127.0.0.1:8081/otp;
    }

    location /images {
        proxy_pass http://127.0.0.1:8081/images;
    }
}