Me and my wife had HDHP plans with different employers (Wifes plan had kids). I had HSA and she did not. Can I contribute to my HSA $6,900 for my entire family?

[BMcCalpin]

Yes.

If your spouse has Family HDHP coverage and you have Self-only HDHP coverage, you are required by the IRS to report that both of you have Family coverage.

When TurboTax sees that you have Family coverage, then it will allow contributions up to $6,900 to your HSA. Note that you need to take into account any contributions you have already made to your HSA in 2018.

NOTE!!! You need to make this extra contribution for 2018 before April 15th, so don't delay.

Also note that you must tell the HSA custodian that the contribution is for 2018, because their default is to make it for the current year, 2019.