I see this is a few days ago that you posted & I've read through some of the replies & your responses & some references to other posts, to try to get a "bigger picture" & there are some things that I noted.
If I have this right, I see the money is to help with fuel to visit family then get to work. I have to be honest in that, as for visiting, I would tell someone that if you can't afford the travel costs then you don't go, this isn't a necessity, but I understand seeing family is very important to many, children love seeing grandparents & depending on the age of grandparents those opportunities to see them could not be there in the near future....
Personally I see no problem in borrowing the childrens money as long as you are sure you can pay it back, it's going into an ISA, so they can't spend it, so they lose nothing.
BUT....
Regardless of whether you use the children's money or credit cards, maybe this is your sign to take a look at how you are managing finances.
You say you are paid well, so the question is, why would you be running out of money & why have you no savings?
I have helped many people sort out their finances over the years, one of the most common problems is people being paid monthly. With people running out of money before the end of the month, we work on breaking their finances down to weekly amounts, the goal is to have a set amount each week to spend.
I was finding people were saying, "I have no money this week because X is being paid this week" eg: X = any bills/DDs like Mortgage, Rent, Gas, Electric etc, so we would work on building up enough money so a person is like a month ahead financially, so all bills etc didn't matter what they day they left the bank, a person would still have the same amount of money every week of the year. Another issue was people not budgeting for things like birthdays, Xmas, so we would set a budget & these would be planned for, each month a set amount was put in a savings account just for these occasions, included would be presents, food, travel.
There should always be the emergency fund, I always ask "if your washing machine/cooker/boiler breaks can you afford to replace it without getting into debt?"
Prioritising is important, so with budgeting, it's daily expenses first, then other essentials that aren't necessarily weekly like your clothing, shoes, the emergency fund takes priority over birthday/Xmas fund. In some cases people have told family that they are no longer to buy Xmas/birthday presents for each other, sometimes it needs to stop, you don't need to buy for all your niece's, nephews, cousins, even your brother & sisters, if your situation needs it.
Finally if a person is in the position you have the luxury fund, that's your holidays, concerts, day trips, luxury items, jewellery, tech etc.
We also look at ways of saving money, better ways to shop, cheap meals, ways of making little bits of extra money, eg: cashback sites, if people are good at budgeting, cashback credit cards, use for your daily spending & pay in full at the end of every week/month.
Often people are shocked when they break down their finances & spending & just how much money they are wasting & how much they could have saved..this includes people who thought they were managing their finances & budgeting well, thinking they just didn't have enough money to get them through the month.
It doesn't take long to go through your incomings & outgoings, breaking it all down & rejigging so you don't end up in situations like this, if you need to ask a trusted person or an advisor to help you do it.