Hi Rasmus,
I apologize for the misunderstanding as far as linking to a different template is concerned.
You are wanting a template that pulls the most recent post from a channel, correct? You want that template to include comments that are associated with that entry, correct? This scenario, for the most part, describes a single entry template. The second block of template code above will do what you are looking for.
In the instance where you want to pull the most recent entry, you just supply {exp:channel:entries} with the limit=“1” parameter. That will cause it to pull the most recent entry from the channel. You needn’t be concerned with supply the {exp:comment:entries} tag with any additional information. By being included in the single entry template, ExpressionEngine will supplying the comment block with the information it needs dynamically.
Plug this code into a template:
{exp:channel:entries channel="my_channel" limit="1"}
{title}
{body}
{/exp:channel:entries}
{exp:comment:entries channel="my_channel" sort="asc" limit="20"}
{comment}
By {name} on {comment_date format="%Y %m %d"}
{/exp:comment:entries}
And see if you don’t automatically get the results you desire. Be sure to change the channel=“” parameter to match your actual channel name.
Let me know if this working example code gets you what you are looking for.
Best,