Provide guidance on splitting 1099 income in MFS returns

hi everyone and t.i.a. a quick-ish history and then ask, below. i am now on year 3 of enormous accountant headaches. quick summary is that we are an "expat" couple ( USA citizens), one of us currently earns income ( and uses the FEIE ) via her LLC. we have some smaller 1099 income ( interest from bank accounts, dividends, this year some cap gains ), but otherwise have a fairly simple tax situation. ( no kids, properties, rental incomes, retirement account contributions, etc. ) you'd think our tax prep would be easy, but we've run into numerous issues, stemming from any of: a) using the 'mid-tier' of 2 different expat-focused tax prep services. ( saying 'mid-tier' as most of these seem to have 3 levels/prices: low -> use their web app + they don't review anything or give feedback; mid -> use their web app + they do professional review and submit; high -> they do all for you. ) our life experience is that externalizing the bulk of the work ( i.e. using high tier ) leads to F-ups and we then have to go through everything with a fine-tooth comb anyway to catch mistakes. separately, we didn't want to have to fight with a company about what constitutes reasonable courtesy/free feedback ( i.e. low tier ) ( e.g. we don't know how to answer question 22 because the wording is confusing / a check-box option that should be there isn't there, interpreted as " you are asking us for expertise, pay us more "). both times, we've found the CPAs at these companies don't know their basics about expat taxes, FEIE, or even how their own website works ... and we've been forced to sit through months-long delays and countless email threads where we are pressured to upgrade or they won't file for us. even pointing out blatant errors doesn't help ( e.g. not understanding that business expenses and part of self-employment tax can't be excluded under FEIE ). we won't use a company like this again. b) one year, we had residency in another country, so used a ( well-reviewed! ) service that offered prep for both that country and USA. the USA taxes were so rife with errors that it's not even worth going into. but just one: multiple numerical typos in spouse's SSN on form, error was pointed out explicitly, next draft had same error, pointed out again, fixed one of the numbers, not the other. ( there were substantial errors as well, but this example gives a nice flavor. ) c) last year, after our experience with (b) (and thus not allowing (b) to submit for us), trying one of the services in (a) and also not being able to submit, we used a smaller boutique prep service for USA. they did an okay job, although made a big mistake that would have cost us four-figures had I not caught it ( applying the foreign-housing exclusion to me, who had no income, instead of my spouse, who had excess beyond FEIE ). otherwise was an okay experience and, due to exhaustion from (a) and (b) in past years, decided to continue with this firm. and, because i had to do something more complex last tax year ( selling some stock to try to take advantage of a period of no earned income for myself ), i booked a paid call with the cpa late last year to feel out the idea, make sure everything was kosher, and that my assumptions about sales and incoming splitting ( MFS stuff ) was sound. he definitively said it was. fast forward to this year during tax prep time, and this CPA is doing a complete 180 on his advice ( i have detailed notes from the call, as well as emails where he agrees with the main points ) ... leaving us likely owing several thousand in taxes that we would not have owed with the proper advice ( i.e. i would have taken different steps while still in 2024 ). cpa dropped this bomb and then promptly went on vacation and put up an auto-reply, so we are still in the midst of this fairly-enraging situation. all of which brings me to my main point: with the right community help and possibly the right non-proprietary software (see my issues with (a), above, regarding proprietary software)...would i be able to file totally on my own? i have a decent ( hard-won, unfortunately ) knowledge at this point and am having to spend so much time and money on fixing ( bad ) help that i'd rather just cut it out completely. we need to be able to do a filing that supports: \- FEIE / expat taxes \- MFS ( at least this year ), which I know is two separate returns that are linked up somehow \- business ( single member LLC, regular pass-through / not an S-Corp ) income and expenses \- normal-looking 1099s. note that we are not in a state that requires 50/50 income split for these accounts, so want to be able to assign this income to one of us or another in a justifiable/logical way ( account ownership, or in the case of capital gains a chronological logic around who funded what and when ) which would lead to more like a 70/30 split. put more simply, we want the ability to split up a 1099's income into each of the MFS returns, which is a new process for me. many thanks for your feedback...i truly hope this can be done without having to rely on another unprofessional professional: my poor little heart can't keep this up for multiple more years.