Serbinski Accounting Firms

I have read conflicting information about this form. The IRS says that it is now obsolete. I know that people in their past filings had to complete this form and may need to continue. If I have never completed this, is there any benefit to completing and submitting it? Will it help when it comes ...

Is there a way to use the tax paid or accrued on the deemed disposition of stocks as a foreign tax credit on either a 1040NR or 1040? thanks.

I moved to the US in 2015, but did not sell the holdings in these 2 accounts to get an increased cost basis (bump up?). Is there anything that I can do now, as I am now just completing my 1040 to take advantage of this? Thank you.