looking at this, costargh, sorry about your loss. You should consider what category to apply for, as you can only apply for once for a particular incident.
1) for long term effects, such as the loss of your grandparents, should be listed in SEAS. these require an impact statement as well as documents where required. Talk to your careers advisor about these. SEAS application may allow you to be admitted in a course where you do not have high enough ENTER or do not meet the minimum score on prerequisites. Accounting for last year's loss should definitely be noted in SEAS as this can be used to appeal for your MM score.
2) for disadvantages in year 11/12, such as looking after your grandmother (excessive responsibilities), applies to anything that is not long-term. These help you in a similar manner.