Tier 2 dependent for shorter duration

[DrAAA]

I need advice regarding my tier visa please.
I am currently on tier 2 visa valid until sep 2023 and I can get an Indifinite to leave in 3 years from now.
I need to apply for my family until July 2022 only as they are going to get the ILR too.
My question is; can I apply for a 3 year visa for my dependents while my visa is valid for 4 years or it has to be inline with my visa

[CR001]

How do you dependents qualify for ILR in July 2022?

What is their full immigration history?

Your dependents will likely get the same visa validity as you.

[DrAAA]

We arrived at the UK together September 2017.
Our first visa is valid from July 2017 and I guess this means they qualify for ILR in July 2022.
I changed employer and I got a 5 year COS which gave me 4 years of validity on my Visa till 2023.
Now trying to apply for their extension and I wanted to apply for 3 years only but IHS whenever I enter my visa details give me no option for 3 years.
Is there a way to get them 3 years visa or they have to have a 4 years like mine as it will cost much more and for no extra benefit.

[CR001]

When do their current visas expire?

They will get a visa with the same expiry as you and have to pay accordingly.

[DrAAA]

Thanks for your answers.
Their visa expires 14/7/2019 and I am going to apply for extension.
(I think I can apply now as they have less than 60 days remaining is that right? )
Also the ILR is from the date of the first visa not entry to the UK as I know. So I think we will be able to apply to ILR July 2022.
If this is the case then I could have extented for 3 years only but now I will have to apply for 4 years visa I guess.