Alternate weekends with an evening or overnight in between is the bare minimum for a standard non-primary parent. She may make it sound like it's a 'gift' but it's really a minimum level. Most here are advised to start out seeking 50% time or even majority time. Yes, the ex will go ballistic and the court may tut-tut and look for ways to give the father minimal time while also emptying his pockets, but the point is that (1) you want to be a very involved parent and (2) you have substantive concerns about the parenting of the other parent.
Courts prefer to have alternated weekends. It's a time-proven schedule that works for most people. You may be able to wrangle a majority of the weekends, such as weekends 1, 3 & 5 each month or something similar, but I doubt you can get them all.
At a minimum you should seek 50% parenting. For example, with younger children this schedule would work for you, it's called a 2/2/5/5 schedule or some numeric order variation:
Mon & Tue overnights - Mother
Wed & Thu overnights - Father
Fri - Sun overnights - alternated between parents
Though initially the court will be inclined to default to mother having temp custody and majority time, since you both work, you'll be able to (try to) avoid the "father works so mother gets temp custody" solution. In my temp order that was the magistrate's only question, "what are your work schedules?" So I became alternate weekend parent for the next
two years until the final decree where I moved up to 50%. That's why you MUST try to get the very best order from the start, at that first hearing before the judge you need to express your concerns about mother's parenting, you'll be locked into it for a long, long time.
Clearly, this is not a time to be timid, so stand up for your parenting and your children. If you aren't
proactive and assertive, you'll be run over both by ex and by the professionals just filling in the blanks for typical orders. And don't be fooled by your form-filer lawyer who says, "Yeah, it's a lousy order, don't worry, keep quiet, I'll get it fixed later." Um, news flash, the fix may be minimal and take a couple years.
Even if the children aren't in school yet, try to be assigned as
Residential Parent for School Purposes. Prepare for it by becoming as involved as possible in the children's schools, PTA, meeting the teachers, etc. That will give you a slight edge, maybe.
In this quote our reasonably normal parent is female, so just switch the genders in the text.
Why try for the best possible order from the very first hearing? The old saying... . nothing ventured, nothing gained. I also phrase it this way, if you ask for it you might get it, if you don't ask for it you won't get it.
Most courts consider custody as separate from parenting time. Find out how your state and local courts handle it. She may have to live with joint legal custody but the amount of scheduled parenting time can be a separate matter altogether.
She should seek full custody (may take a custody evaluation to get a professional to recommend it) but include a secondary option, that if the court declines to grant her full custody, then she asks for tie-breaker or decision-making status in joint custody. That way she can still do her parenting without the predictable obstructions and without having to resort to Parenting Coordinators, mediators or going back to court over and over...
All courts see alternating weekends as normal for separated or divorced parents. (In some cases they make it first, third and fifth weekends, a minor variation to alternate weekends. They don't expect one parent to get all the weekends without basis to do so. And no, being in-patient or incarcerated is not basis. However, that might be basis not to be guilted into it.) Exceptions are for professions such as firefighters, policemen, etc who have unusual schedule requirements. So there was no reason for her to allow him to have all four recent weekends.  :)id he guilt her into allowing that, calling it makeup for while he was unavailable? If so, then she should have held firm to a normal alternate weekend schedule. As an example, in my case when my ex and I were separated and between parenting time orders, she blocked all my father-child contact for 3 months while I filed and waited for the next court date. Three months of zero contact without basis, do you think the court felt bad for me and gave me make-up time or gave my ex harsh consequences? No, the magistrate just confirmed from ex she had blocked 3 months and merely said, "I'll fix that, I'll make a new temp order" same as the old temp order with me getting minimal alternate weekends. My point is that court often ignores the past conflict and doesn't order make-up time, so no need for your sibling to be guilted into it.
Courts often ignore incidents older than six months before filing as 'stale' or 'not actionable' but such incidents in the past can count as history or pattern of behaviors.
Many courts effectively ignore mental health labels concluding they don't know how much it affects the parenting. Realizing that, your sibling needs to be careful not to "play doctor" claiming mental health labels or diagnoses. Even if she gets a diagnosis, that's not what counts most. She needs to do what most professionals and the courts do, focus on the behaviors and behavior patterns. While she can mention the poor adult behaviors, she should give priority to his poor parenting behaviors since that is what the courts give priority attention.
In my case (similar to what most members here have experienced) my ex was never diagnosed, however, her parenting behaviors became the determining factors. The custody evaluator's initial report stated, "Mother cannot share 'her' child but Father can."