She can have a maximum of 520 Jobseekers credits Reckonable for the Contributory Pension. This is on top of her 312 Homemakers credits.
If she currently has no Jobseekers Credits she has the capacity to use Reckonable Jobseekers Credits for up to 10 years instead of class S from her ARF.
It would make sense to carry out the plan you described.
As she is out of the prsi system for more than 2 years she needs a minimum of 26 full rate paid contributions to get back into the Prsi system in order to qualify for Jobseekers credits.
If she initially gets 2 years of class S from her ARF she will satisfy this rule.
She might or might not then need to get one paid class A contribution.
( not too sure about this )
Jobseekers credits based on class S are not allowed.
Then she can sign on for Reckonable Jobseekers Credits.
She should continue signing on for Jobseekers credits, at least up to the end of the calendar year of her 63rd birthday. This is necessary if she wants to qualify for Benefit Payment 65.
She won't qualify for Benefit Payment 65 based on the class S from her ARF.
The reason for this is because it is necessary to cease a self employment in order to qualify under class S rules.
In order to qualify for Benefit Payment 65 she would also need 13 weeks of paid class A contributions in any one of the calendar years of either her 61st, 62nd, 63rd, 64th or 65th birthdays.
She can have a mix of class A, class S and Jobseekers Credits in any particular year.
It's a good idea to be in both the class A and class S Prsi systems, as the rules for qualification for the Contributory pension and BP 65 could change in the future.
Keep all options open.