Tier 2 ICT - Maternity / Long Term Sickness Leave

[narass]

Hi Team. My wife is working in UK under Tier2-Intra Company Transfer (long term staff) visa category from Dec'2010. We had our baby while in UK in the month of May'2018.
Because she is on Tier2-ICT visa category, initially employer had refused to provide her maternity leave. So she had to take unpaid leave for 6 months from Jun'18 to Nov'18.
Once she joined back to work in December she could manage to work only for 2 months (till Jan'19) because of ill health.
Because her health condition got deteriorated she is undergoing treatment through NHS in UK hence she is on leave from Feb'19 till now (Jul'19) under long term sickness category.

Could you please clarify on below queries:
1. For how many months she is allowed to take leave under long term sickness category while working in UK ? Is there a cap on this leave category ?
2. How many months of Maternity leave is allowed under the Tier2-Intra Company Transfer category ?
3. Since she took unpaid leave for 6 months (from Jun-Nov 2018) + worked for 2 months + Long term sickness Leave for 6 months (from Feb to Jul 2019),
a. will there be any issue from employer or UKBA ?
b. Will UKBA treat this as a 12 month break from work (considering 6 months unpaid leave + 6 months long term sickness) ? or will they take only the latest 6 months leave (long term sickness leave) into consideration ?
c. If UKBA treats it as a 12 months break, will they create any complications with her Work Visa ? Will this Visa become invalid (even if she has visa for another one year) and will she be asked to travel back to home country ?