My sister wants six months between our weddings. Do we need to change our date?

My sister said, "I thought we'd have the year to ourselves." Her wedding is booked, and we've just been offered a date six weeks after it at the venue we wanted.

We haven't paid yet. She worries that relatives travelling for both weddings will face two expensive trips close together. I think that is a fair concern. She also says the second wedding will take attention from hers, which is harder for me to answer.

The other date the venue can offer us is the following year. We'd prefer to marry sooner. Some shared relatives live nearby, while others would need flights and hotels, and we haven't asked what either date would mean for their plans.

I don't want our guest lists turned into sides. How do we make our decision while taking the actual travel burden seriously, without promising that no family wedding can happen for six months around another one?