As told to Ann DeGrey

Looking after an elderly parent is very difficult. Looking after one with dementia is heartbreaking.

My sister Polly* and I took it in turns to care for our mum, who's now in the later stages of dementia. Mum still lives at home, and while we've talked about full-time care, we both agreed we wanted to keep her in her apartment for as long as possible. We split the week evenly, with Polly staying a few nights, while I do the rest of the week. It wasn't perfect, but it seemed to work.

But a few months ago, I started noticing strange withdrawals from Mum's bank account.

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It started off with little things, like unusual transactions from the local ATM late at night. Then bigger sums of money left her account, $500 at a time, sometimes more. It's like the money was disappearing with no explanation. Mum had always been super careful with her money. Even with her memory fading, she was never reckless at all.

She didn't shop online or use her bank card unless someone helped her. I managed most of her bills, so I knew what should and shouldn't be coming out of her account. So I raised it with Polly.

She got defensive straight away and said I was being dramatic, that maybe Mum had forgotten a few purchases, or that I'd made a mistake with the statements. But I'd printed them out and highlighted every dodgy charge. There was no denying the money was going somewhere it shouldn't!

Then she said something that really stuck with me: "It's nothing to do with me."

It was quite a weird response. I hadn't accused her directly, all I did was ask if she'd noticed anything. But the way she shut down the conversation so quickly was very odd to me and really raised alarm bells.

About a week later, Polly called a family meeting, saying she had important news. My cousins came over, and we were all expecting something serious, like about Mum's health. Instead, she sat down with a big smile on her face and announced she was pregnant. I was stunned!

Polly is 42 and has always said she didn't want kids. She's been with her current partner, Dan, for just three months. I'd only met twice and very briefly, so this news came out of nowhere.

Our family congratulated her and everyone was happy, but as the days went on, no one was talking about Mum's bank account anymore. Even I felt swept up in the happy baby news because it felt like a miracle. But something didn't sit right with me.

Polly didn't show much interest in things like talking about doctor's appointments or scans. She didn't share ultrasound pictures or mention morning sickness.

Weeks passed, then months. And while she did start wearing looser clothes, her body hadn't changed at all. I had a strange gut feeling that something odd was going on. I quietly started keeping closer track of Mum's finances. I limited access to her accounts and moved some of her savings into a more secure setup.

That's when I saw the extent of the damage; nearly $10,000 had disappeared in less than five months. So I knew I had to confront Polly again.

When I finally got her on the phone, I asked two direct questions: was she really pregnant? And had she taken money from Mum? There was a long silence and then she started crying.

She admitted that there was no baby. She'd faked the pregnancy to distract everyone (mostly me) from noticing the money missing. She said she was in debt, that her partner had lost his job and that she didn't know what else to do. She thought if she could just buy time, she could replace the money before anyone found out.

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I was horrified! My own sister, using our vulnerable mum's money and lying about something so sacred as a pregnancy, just to cover her tracks. I told her I wouldn't report her, but that she was no longer welcome to stay at Mum's house or have access to her accounts. I changed every password and made sure Mum's care was handled properly going forward.

Polly asked me not to tell the rest of the family, but I did. They deserved to know the truth and now hardly anyone speaks to Polly now. These days Polly texts sometimes, but mostly short messages to ask how Mum is. I reply, but I keep things distant.

I still love my sister, but I'll never trust her again.

*Names changed to protect identities

Feature Image: Getty (Stock image for illustrative purposes).