Thanks for all your help in my previous queries. Here is another one please

I got my ILR (Tier 1 + Tier 2 G - 5 year route) in March 2019.
I am now going to apply ILR for my dependants [wife + 1 child (born outside UK)]
Their visa and residence history is as below:
Tier 1 G Dependant visa: 22/06/2014
1st entry: 08/07/2014
Left UK: 08/10/2014
2nd Entry: 02/08/2015 (after 298 days OR 9 months, 26 days)
After that there is no long absence from UK.
Questions:
1. When they can apply for ILR?
2. When would 28 days threshold starts for them; from date of visa or from date of 1st entry?
2. Which application form they should use?
3. Could long absence spanning into 2 years be a problem form them regarding continuous residency?
Many thanks in advance.
Regards,
Confused!