Drama theories:
1. Jill is adopted, because of the shame that her sister bring to her family
2. Her sister is actually MC's mother
3. Isabella & Neill were couple back in the days... and they loved each other deeply
4. The relationship between Bella & Neill probably is the reasons behind the death of MC's mother and the missing husband of Bella.
5. Neill is not the biological father of MC, his partner is, MC's mother slept with both of them during the renovation
6. Burke know about the whole situation between Neill, Bella & MC's mother, that's why he has all this power in B&R, because he keeps the Royce secret safe.