CTT: How to make a link to the transition form to create a message in an existing discussion?

Question

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Now, if you make a link to a discussion, then the first message of the discussion is displayed by default, but you need the link to immediately display the message entry form.

Answer 1

To display ONLY the form:
vk.com/topic-1_21972158? offset=99999
To display the latest message, you need to know its ID, for example:
vk.com/topic-1_21972158?post=82429 _
UPD: Updated by adding working links so you can see the result right away.

Answer 2

vk.com/topic-1_1?offset=99999

Offset=99999 is this the default setting? Will it work even when the number of posts in a topic is greater than 99999?