In the colonies it was relatively common to pressure other powers to abandon their claims to colonial territories.
To start with, Russia did not have colonies. Alaska was a part of the Russian Empire administered by RAC. If AII decided to hold Alaska, the RAC administration (which was appointed by the government) would be most probably replaced with the standard Russian administration. So you have not a colonial dispute but a direct aggression.
One need only look at the controversy in Portugal over the "cor de rosa map" to see an example of Great Britain pressuring a country to renounce claims in the colonies in favor of it. (To make it worse, Portugal was a British ally.)
FYI, Russian Empire had a slightly different international status than Portugal so example is hardly relevant.
Do that to a Russia Britain is dying to give a black eye to? They would certainly consider it.
Only if there is an ongoing war between these two. The last chance for Britain was the CW.
BYW, closer to the end of the XIX century the Russian
military presence on the Pacific coast seriously increased due to the improved communications by the Amur and, if needed, the reinforcements could be brought to Alaska.
The rest of the powers of Europe would be happy to support Great Britain in something that involves screwing up Russia without any danger to them, since anyway much of their policy was based on "containing" Russia because "balance of powers" .
An idea that the main goal of all European powers in the XIX century was to screw Russia is British (or rather Palmerstonian) pipe dream which did not came to existence even during the CW. For example, in the early 1870s Bismark was offering Russia to screw Britain by rebuilding the Black Sea fleet. There was Alliance of Three Emperors and later the close Franco-Russian relations. If anything, in your schema it is Britain who disturbs the balance of power.
Like I said, "Germany part" would require Germany to be smart enough to see that this is an opportunity to get closer to Russia.
Germany already
was close to Russia. Even Congress of Berlin did not completely change this.
The problem is that I suspect they would read that as "proof" that Russia is weak and therefore worth putting pressure on them (eg to weaken them and make them useless in an alliance with France).
I have no idea which time frame you are talking about and how exactly and why Germany of the late XIX would try to weaken Russia.
Where in the phrase of Great Britain trying to expand into Afghanistan did I imply that they would be successful? I don't remember saying they were successful.
You did not but you missed the point: in the late XIX Afghanistan already was within the British sphere of influence as per British-Russian agreement and there was no need for the Brits to move into it in any meaningful way.