The Moneyist: ‘There’s a good chance I’ll get early-onset Alzheimer’s.’ How do I divide my estate between my girlfriend and daughter? Do I ask them first?

Dear Moneyist,

I’m considering proposing to a long-time girlfriend, but unsure how to handle division of assets down the road. I have been married previously and have a high-school aged child. She has no kids, and there are no plans for any in the future. I have fairly sizable assets within my retirement savings, brokerage accounts and a paid-off home.

The kicker is that there’s a good chance I will get early-onset Alzheimer’s within the next 10-15 years (one of my parents got it in their late 50’s, which means it’s probably hereditary). I haven’t been tested for the gene and I’m not planning on it, but it’s with a high level of certainty, I’ll get it. My girlfriend is fully aware of this.

That said, I’m trying to plan financially so that my healthcare doesn’t become a burden, which is my biggest priority. But in terms of modifying my will for what’s left over, I’m having trouble. I have my own assets that I’ve accumulated, and a sizable portion of assets that were left to me by my grandparents and one parent.

The Moneyist:I married my husband 20 years ago. He has 4 kids and I have 1. I paid for our home. Who should inherit it after we’re gone?

Is it wrong to leave funds passed down from generation to generation solely for my daughter, and leave other funds to my new wife? While I want my wife to have ample funds given that she will more than likely live at least another 15-plus years without me, she also will have a decent pension plan from her own place of work.

Dividing up assets is hard when you’ve been married before and have kids, but the high potential of an early terminal illness adds another complexity. Is it something we should discuss, or should I simply make these decisions on my own? I can see how each way could raise some tension that I don’t want. What are your thoughts?

Contemplating Marriage

The Moneyist: My wife found a half brother through Ancestry.com. Are we morally or ethically obligated to share her father’s estate?

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Dear Contemplating,

It’s more than fair to make sure that your daughter is taken care of and inherits 100% of the inheritance passed down to you from your grandparents. They would want that. It is also a way to help your own grandchildren, should your daughter change her mind and decide to have children.

Your daughter should be your No. 1 priority. If you are going to ask anyone’s advice, let it be hers. She is currently your only legal heir, and it is fair and reasonable to want to discuss your estate planning with your daughter. After you have her perspective, you can raise it with your girlfriend.

The only thing anyone should ever bet on receiving from a marriage is commitment and honesty. No one should enter marriage with the expectation that they are going to make out financially. You can, of course, take your respective assets into account, but they should not be a motivating factor.

The Moneyist:My spendthrift fiancée, 30, refused to sign a prenup. Would it be wrong to secretly put my assets in a trust?

She would also benefit from your own retirement funds, and Social Security. You can lay out your plans ahead of time. You’re not asking her permission, but you can always ask her for her feedback, and thoughts. You can decide to take them into account, or not.

In an ideal world, we fall in love with the expectation of nothing of a material nature in return. I don’t think your girlfriend would be with you for any other reason than because she loves you, especially if she shares your outlook on your possible prognosis.

I do hope you are wrong about your own health, and I respect your decision not to test for the gene. It’s important to plan for all likely or possible eventualities, but also to remember to enjoy the moment. I hope that you have many, many more.

The Moneyist:My sister became my father’s power of attorney, took out a reverse mortgage, and drained his equity. What can I do?

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Quentin Fottrell is MarketWatch’s Moneyist columnist. You can email The Moneyist with any financial and ethical questions at qfottrell@marketwatch.com. By emailing your questions, you agree to having them published anonymously on MarketWatch.